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• What's the difference between UI development and front-end development?

  - by Nick Lowman

  I'm a front-end developer and really enjoy jQuery and JavaScript. I've built a lot a websites, done some good jQuery work and built a few JavaScript based applications and would really like to get in UI development. Or so I thought. I guessed it would be pretty similar to what I already do except maybe a little more JavaScript heavy but when I looked into it all the job specs said I needed to know about Scrum or Agile development, knowledge of testing frameworks and a good knowledge of JavaScript frameworks and custom events. So, from the specs I get the idea that a UI developer is actually a dedicated JavaScript developer. Is that the case? I understand (with much help from the users on stackoverflow), about JavaScript OO, inheritance, closures, custom events, debugging in Firefox or Aptana etc, and the people I work with seem to think I pretty OK at what I do but clearly my knowledge is not good enough to go for UI jobs. If anyone could tell me a little more about UI development and if there are any good resources for learning about it I would be most grateful as I couldn't find much on the internet.

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• Creating Property Set Expression Trees In A Developer Friendly Way

  - by Paulo Morgado

  In a previous post I showed how to create expression trees to set properties on an object. The way I did it was not very developer friendly. It involved explicitly creating the necessary expressions because the compiler won’t generate expression trees with property or field set expressions. Recently someone contacted me the help develop some kind of command pattern framework that used developer friendly lambdas to generate property set expression trees. Simply putting, given this entity class: public class Person { public string Name { get; set; } } The person in question wanted to write code like this: var et = Set((Person p) => p.Name = "me"); Where et is the expression tree that represents the property assignment. So, if we can’t do this, let’s try the next best thing that is splitting retrieving the property information from the retrieving the value to assign o the property: var et = Set((Person p) => p.Name, () => "me"); And this is something that the compiler can handle. The implementation of Set receives an expression to retrieve the property information from and another expression the retrieve the value to assign to the property: public static Expression<Action<TEntity>> Set<TEntity, TValue>( Expression<Func<TEntity, TValue>> propertyGetExpression, Expression<Func<TValue>> valueExpression) The implementation of this method gets the property information form the body of the property get expression (propertyGetExpression) and the value expression (valueExpression) to build an assign expression and builds a lambda expression using the same parameter of the property get expression as its parameter: public static Expression<Action<TEntity>> Set<TEntity, TValue>( Expression<Func<TEntity, TValue>> propertyGetExpression, Expression<Func<TValue>> valueExpression) { var entityParameterExpression = (ParameterExpression)(((MemberExpression)(propertyGetExpression.Body)).Expression); return Expression.Lambda<Action<TEntity>>( Expression.Assign(propertyGetExpression.Body, valueExpression.Body), entityParameterExpression); } And now we can use the expression to translate to another context or just compile and use it: var et = Set((Person p) => p.Name, () => name); Console.WriteLine(person.Name); // Prints: p => (p.Name = “me”) var d = et.Compile(); d(person); Console.WriteLine(person.Name); // Prints: me It can even support closures: var et = Set((Person p) => p.Name, () => name); Console.WriteLine(person.Name); // Prints: p => (p.Name = value(<>c__DisplayClass0).name) var d = et.Compile(); name = "me"; d(person); Console.WriteLine(person.Name); // Prints: me name = "you"; d(person); Console.WriteLine(person.Name); // Prints: you Not so useful in the intended scenario (but still possible) is building an expression tree that receives the value to assign to the property as a parameter: public static Expression<Action<TEntity, TValue>> Set<TEntity, TValue>(Expression<Func<TEntity, TValue>> propertyGetExpression) { var entityParameterExpression = (ParameterExpression)(((MemberExpression)(propertyGetExpression.Body)).Expression); var valueParameterExpression = Expression.Parameter(typeof(TValue)); return Expression.Lambda<Action<TEntity, TValue>>( Expression.Assign(propertyGetExpression.Body, valueParameterExpression), entityParameterExpression, valueParameterExpression); } This new expression can be used like this: var et = Set((Person p) => p.Name); Console.WriteLine(person.Name); // Prints: (p, Param_0) => (p.Name = Param_0) var d = et.Compile(); d(person, "me"); Console.WriteLine(person.Name); // Prints: me d(person, "you"); Console.WriteLine(person.Name); // Prints: you The only caveat is that we need to be able to write code to read the property in order to write to it.

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• How can I inject Javascript (including Prototype.js) in other sites without cluttering the global na

  - by Daniel Magliola

  I'm currently on a project that is a big site that uses the Prototype library, and there is already a humongous amount of Javascript code. We're now working on a piece of code that will get "injected" into other people's sites (picture people adding a <script> tag in their sites) which will then run our code and add a bunch of DOM elements and functionality to their site. This will have new pieces of code, and will also reuse a lot of the code that we use on our main site. The problem I have is that it's of course not cool to just add a <script> that will include Prototype in people's pages. If we do that in a page that's already using ANY framework, we're guaranteed to screw everything up. jQuery gives us the option to "rename" the $ object, so it could handle this situation decently, except obviously for the fact that we're not using jQuery, so we'd have to migrate everything. Right now i'm contemplating a number of ugly choices, and I'm not sure what's best... Rewrite everything to use jQuery, with a renamed $ object everywhere. Creating a "new" Prototype library with only the subset we'd be using in "injected" code, and renaming $ to something else. Then again I'd have to adapt the parts of my code that would be shared somehow. Not using a library at all in injected code, to keep it as clean as possible, and rewriting the shared code to use no library at all. This would obviously degenerate into us creating our own frankenstein of a library, which is probably the worst case scenario ever. I'm wondering what you guys think I could do, and also whether there's some magic option that would solve all my problems... For example, do you think I could use something like Caja / Cajita to sandbox my own code and isolate it from the rest of the site, and have Prototype inside of there? Or am I completely missing the point with that? I also read once about a technique for bookmarklets, were you add your code like this: (function() { /* your code */ })(); And then your code is all inside your anonymous function and you haven't touched the global namespace at all. Do you think I could make one file containing: (function() { /* Full Code of the Prototype file here */ /* All my code that will run in the "other" site */ InitializeStuff_CreateDOMElements_AttachEventHandlers(); })(); Would that work? Would it accomplish the objective of not cluttering the global namespace, and not killing the functionality on a site that uses jQuery, for example? Or is Prototype too complex somehow to isolate it like that? (NOTE: I think I know that that would create closures everywhere and that's slower, but I don't care too much about performance, my code is not doing anything that complex)

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• Unique element ID, even if element doesn't have one

  - by Robert J. Walker

  I'm writing a GreaseMonkey script where I'm iterating through a bunch of elements. For each element, I need a string ID that I can use to reference that element later. The element itself doesn't have an id attribute, and I can't modify the original document to give it one (although I can make DOM changes in my script). I can't store the references in my script because when I need them, the GreaseMonkey script itself will have gone out of scope. Is there some way to get at an "internal" ID that the browser uses, for example? A Firefox-only solution is fine; a cross-browser solution that could be applied in other scenarios would be awesome. Edit: If the GreaseMonkey script is out of scope, how are you referencing the elements later? They GreaseMonkey script is adding events to DOM objects. I can't store the references in an array or some other similar mechanism because when the event fires, the array will be gone because the GreaseMonkey script will have gone out of scope. So the event needs some way to know about the element reference that the script had when the event was attached. And the element in question is not the one to which it is attached. Can't you just use a custom property on the element? Yes, but the problem is on the lookup. I'd have to resort to iterating through all the elements looking for the one that has that custom property set to the desired id. That would work, sure, but in large documents it could be very time consuming. I'm looking for something where the browser can do the lookup grunt work. Wait, can you or can you not modify the document? I can't modify the source document, but I can make DOM changes in the script. I'll clarify in the question. Can you not use closures? Closuses did turn out to work, although I initially thought they wouldn't. See my later post. It sounds like the answer to the question: "Is there some internal browser ID I could use?" is "No."

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• Closure Tables - Is this enough data to display a tree view?

  - by James Pitt

  Here is the table I have created by testing the closure table method. | id | parentId | childId | hops | | | | | 270 | 6 | 6 | 0 | 271 | 7 | 7 | 0 | 272 | 8 | 8 | 0 | 273 | 9 | 9 | 0 | 276 | 10 | 10 | 0 | 281 | 9 | 10 | 1 | 282 | 7 | 9 | 1 | 283 | 7 | 10 | 2 | 285 | 7 | 8 | 1 | 286 | 6 | 7 | 1 | 287 | 6 | 9 | 2 | 288 | 6 | 10 | 3 | 289 | 6 | 8 | 2 | 293 | 6 | 9 | 1 | 294 | 6 | 10 | 2 I am trying to create a simple tree of this using PHP. There does not seem to be enough data to create the table. For example, when I look purely at parentId = 6: -Part 6 -Part 7 - ? - ? -Part 9 - ? - ? We know that parts 8 and 10 exists below Part 7 or 9, but not which. We know that part 10 exists at both 3 and 4 nodes deep but where? If I look at other data in the table it is possible to tell it should be: - Part 6 - Part 7 - Part 9 - Part 10 - Part 9 - Part 10 I thought one of the benefits of closure tables was there was no need for recursive queries? Could you help explain what I am doing wrong? EDIT: For clarification, this is a mapping table. There is another table called "parts" which has a column called part_id that correlates to both the parentId and childId columns in the "closure" table. The "id" column in the table above (closure) is just for the purposes of maintaining a primary key. It is not really necessary. The methods I have used to create this closure table is described in the following article: http://dirtsimple.org/2010/11/simplest-way-to-do-tree-based-queries.html EDIT2: It can have two and three hops. I will explain easier by assigning names to the items. Part 6 = Bicycle Part 7 = Gears Part 8 = Chain Part 9 = Bolt Part 10 = Nut Nut is part of Bolt. The Bolt and Nut combo exists directly within Bicycle and within Gears which is part of Bicycle. In relation to what method to use I have looked at Adjacency, Edges, Enum Paths, Closures, DAGS(networks) and the Nested Set Model. I am still trying to work out what is what, but this is an extremely complex component database where there are multiple parents and any modification to a sub-tree must propogate through the other trees. More importantly there will be insertions, deletions and tree views that I wish to avoid recursion during general use, even at the cost of database space and query time during entry.

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• javascript simple object creation test: opera leaks?

  - by joe

  Hi, I am trying to figure out certain memory leak conditions in javascript on a few browsers. Currently I'm only testing FF 3.6, Opera 10.10, and Safari 4.0.3. I've started with a fairly simple test, and can confirm no memory leaks in Firefox and Safari. But Opera just takes memory and never gives it back. What gives? Here's the test: <html> <head> <script type="text/javascript"> window.onload = init; //window.onunload = cleanup; var a=[]; function init() { var d = document.createElement('div'); d.innerHTML = "page loading..."; document.body.appendChild(d); for (var i=0; i<400000; i++) { a[i] = new Obj("xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"); } d.innerHTML = "PAGE LOADED"; } function cleanup() { for (var i=0; i<400000; i++) { a[i] = null; } } function Obj(msg) { this.msg=msg; } </script> </head> <body> </body> </html> I shouldn't need the cleanup() call on window.unload, but tried that also. No luck. As you can see this is simple JS, no circular DOM links, no closures. I monitor the memory usage using 'top' on Mac 10.4.11. Memory usage spikes up on page load, as expected. In FF and Safari reloading the page does not use any further memory, and all memory is returned when the window (tab) is closed. In Opera, memory spikes on load, and seems to also spike further on each reload (but not always...). But regardless of reload, memory never goes back down below the initial load spike. I had hoped this was a no-brainer test that all browsers would pass, so I could move on to more "interesting" conditions. Am I doing something wrong here? Or is this a known Opera issue? Thanks! -joe

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• Using delegates in C# (Part 2)

  - by rajbk

  Part 1 of this post can be read here. We are now about to see the different syntaxes for invoking a delegate and some c# syntactic sugar which allows you to code faster. We have the following console application. 1: public delegate double Operation(double x, double y); 2:  3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: Operation op1 = new Operation(Division); 9: double result = op1.Invoke(10, 5); 10: 11: Console.WriteLine(result); 12: Console.ReadLine(); 13: } 14: 15: static double Division(double x, double y) { 16: return x / y; 17: } 18: } Line 1 defines a delegate type called Operation with input parameters (double x, double y) and a return type of double. On Line 8, we create an instance of this delegate and set the target to be a static method called Division (Line 15) On Line 9, we invoke the delegate (one entry in the invocation list). The program outputs 5 when run. The language provides shortcuts for creating a delegate and invoking it (see line 9 and 11). Line 9 is a syntactical shortcut for creating an instance of the Delegate. The C# compiler will infer on its own what the delegate type is and produces intermediate language that creates a new instance of that delegate. Line 11 uses a a syntactical shortcut for invoking the delegate by removing the Invoke method. The compiler sees the line and generates intermediate language which invokes the delegate. When this code is compiled, the generated IL will look exactly like the IL of the compiled code above. 1: public delegate double Operation(double x, double y); 2:  3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: //shortcut constructor syntax 9: Operation op1 = Division; 10: //shortcut invoke syntax 11: double result = op1(10, 2); 12: 13: Console.WriteLine(result); 14: Console.ReadLine(); 15: } 16: 17: static double Division(double x, double y) { 18: return x / y; 19: } 20: } C# 2.0 introduced Anonymous Methods. Anonymous methods avoid the need to create a separate method that contains the same signature as the delegate type. Instead you write the method body in-line. There is an interesting fact about Anonymous methods and closures which won’t be covered here. Use your favorite search engine ;-)We rewrite our code to use anonymous methods (see line 9): 1: public delegate double Operation(double x, double y); 2:  3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: //Anonymous method 9: Operation op1 = delegate(double x, double y) { 10: return x / y; 11: }; 12: double result = op1(10, 2); 13: 14: Console.WriteLine(result); 15: Console.ReadLine(); 16: } 17: 18: static double Division(double x, double y) { 19: return x / y; 20: } 21: } We could rewrite our delegate to be of a generic type like so (see line 2 and line 9). You will see why soon. 1: //Generic delegate 2: public delegate T Operation<T>(T x, T y); 3:  4: public class Program 5: { 6: [STAThread] 7: static void Main(string[] args) 8: { 9: Operation<double> op1 = delegate(double x, double y) { 10: return x / y; 11: }; 12: double result = op1(10, 2); 13: 14: Console.WriteLine(result); 15: Console.ReadLine(); 16: } 17: 18: static double Division(double x, double y) { 19: return x / y; 20: } 21: } The .NET 3.5 framework introduced a whole set of predefined delegates for us including public delegate TResult Func<T1, T2, TResult>(T1 arg1, T2 arg2); Our code can be modified to use this delegate instead of the one we declared. Our delegate declaration has been removed and line 7 has been changed to use the Func delegate type. 1: public class Program 2: { 3: [STAThread] 4: static void Main(string[] args) 5: { 6: //Func is a delegate defined in the .NET 3.5 framework 7: Func<double, double, double> op1 = delegate (double x, double y) { 8: return x / y; 9: }; 10: double result = op1(10, 2); 11: 12: Console.WriteLine(result); 13: Console.ReadLine(); 14: } 15: 16: static double Division(double x, double y) { 17: return x / y; 18: } 19: } .NET 3.5 also introduced lambda expressions. A lambda expression is an anonymous function that can contain expressions and statements, and can be used to create delegates or expression tree types. We change our code to use lambda expressions. 1: public class Program 2: { 3: [STAThread] 4: static void Main(string[] args) 5: { 6: //lambda expression 7: Func<double, double, double> op1 = (x, y) => x / y; 8: double result = op1(10, 2); 9: 10: Console.WriteLine(result); 11: Console.ReadLine(); 12: } 13: 14: static double Division(double x, double y) { 15: return x / y; 16: } 17: } C# 3.0 introduced the keyword var (implicitly typed local variable) where the type of the variable is inferred based on the type of the associated initializer expression. We can rewrite our code to use var as shown below (line 7).  The implicitly typed local variable op1 is inferred to be a delegate of type Func<double, double, double> at compile time. 1: public class Program 2: { 3: [STAThread] 4: static void Main(string[] args) 5: { 6: //implicitly typed local variable 7: var op1 = (x, y) => x / y; 8: double result = op1(10, 2); 9: 10: Console.WriteLine(result); 11: Console.ReadLine(); 12: } 13: 14: static double Division(double x, double y) { 15: return x / y; 16: } 17: } You have seen how we can write code in fewer lines by using a combination of the Func delegate type, implicitly typed local variables and lambda expressions.

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• DTracing a PHPUnit Test: Looking at Functional Programming

  - by cj

  Here's a quick example of using DTrace Dynamic Tracing to work out what a PHP code base does. I was reading the article Functional Programming in PHP by Patkos Csaba and wondering how efficient this stype of programming is. I thought this would be a good time to fire up DTrace and see what is going on. Since DTrace is "always available" even in production machines (once PHP is compiled with --enable-dtrace), this was easy to do. I have Oracle Linux with the UEK3 kernel and PHP 5.5 with DTrace static probes enabled, as described in DTrace PHP Using Oracle Linux 'playground' Pre-Built Packages I installed the Functional Programming sample code and Sebastian Bergmann's PHPUnit. Although PHPUnit is included in the Functional Programming example, I found it easier to separately download and use its phar file: cd ~/Desktop wget -O master.zip https://github.com/tutsplus/functional-programming-in-php/archive/master.zip wget https://phar.phpunit.de/phpunit.phar unzip master.zip I created a DTrace D script functree.d: #pragma D option quiet self int indent; BEGIN { topfunc = $1; } php$target:::function-entry /copyinstr(arg0) == topfunc/ { self->follow = 1; } php$target:::function-entry /self->follow/ { self->indent += 2; printf("%*s %s%s%s\n", self->indent, "->", arg3?copyinstr(arg3):"", arg4?copyinstr(arg4):"", copyinstr(arg0)); } php$target:::function-return /self->follow/ { printf("%*s %s%s%s\n", self->indent, "<-", arg3?copyinstr(arg3):"", arg4?copyinstr(arg4):"", copyinstr(arg0)); self->indent -= 2; } php$target:::function-return /copyinstr(arg0) == topfunc/ { self->follow = 0; } This prints a PHP script function call tree starting from a given PHP function name. This name is passed as a parameter to DTrace, and assigned to the variable topfunc when the DTrace script starts. With this D script, choose a PHP function that isn't recursive, or modify the script to set self->follow = 0 only when all calls to that function have unwound. From looking at the sample FunSets.php code and its PHPUnit test driver FunSetsTest.php, I settled on one test function to trace: function testUnionContainsAllElements() { ... } I invoked DTrace to trace function calls invoked by this test with # dtrace -s ./functree.d -c 'php phpunit.phar \ /home/cjones/Desktop/functional-programming-in-php-master/FunSets/Tests/FunSetsTest.php' \ '"testUnionContainsAllElements"' The core of this command is a call to PHP to run PHPUnit on the FunSetsTest.php script. Outside that, DTrace is called and the PID of PHP is passed to the D script $target variable so the probes fire just for this invocation of PHP. Note the quoting around the PHP function name passed to DTrace. The parameter must have double quotes included so DTrace knows it is a string. The output is: PHPUnit 3.7.28 by Sebastian Bergmann. ......-> FunSetsTest::testUnionContainsAllElements -> FunSets::singletonSet <- FunSets::singletonSet -> FunSets::singletonSet <- FunSets::singletonSet -> FunSets::union <- FunSets::union -> FunSets::contains -> FunSets::{closure} -> FunSets::contains -> FunSets::{closure} <- FunSets::{closure} <- FunSets::contains <- FunSets::{closure} <- FunSets::contains -> PHPUnit_Framework_Assert::assertTrue -> PHPUnit_Framework_Assert::isTrue <- PHPUnit_Framework_Assert::isTrue -> PHPUnit_Framework_Assert::assertThat -> PHPUnit_Framework_Constraint::count <- PHPUnit_Framework_Constraint::count -> PHPUnit_Framework_Constraint::evaluate -> PHPUnit_Framework_Constraint_IsTrue::matches <- PHPUnit_Framework_Constraint_IsTrue::matches <- PHPUnit_Framework_Constraint::evaluate <- PHPUnit_Framework_Assert::assertThat <- PHPUnit_Framework_Assert::assertTrue -> FunSets::contains -> FunSets::{closure} -> FunSets::contains -> FunSets::{closure} <- FunSets::{closure} <- FunSets::contains -> FunSets::contains -> FunSets::{closure} <- FunSets::{closure} <- FunSets::contains <- FunSets::{closure} <- FunSets::contains -> PHPUnit_Framework_Assert::assertTrue -> PHPUnit_Framework_Assert::isTrue <- PHPUnit_Framework_Assert::isTrue -> PHPUnit_Framework_Assert::assertThat -> PHPUnit_Framework_Constraint::count <- PHPUnit_Framework_Constraint::count -> PHPUnit_Framework_Constraint::evaluate -> PHPUnit_Framework_Constraint_IsTrue::matches <- PHPUnit_Framework_Constraint_IsTrue::matches <- PHPUnit_Framework_Constraint::evaluate <- PHPUnit_Framework_Assert::assertThat <- PHPUnit_Framework_Assert::assertTrue -> FunSets::contains -> FunSets::{closure} -> FunSets::contains -> FunSets::{closure} <- FunSets::{closure} <- FunSets::contains -> FunSets::contains -> FunSets::{closure} <- FunSets::{closure} <- FunSets::contains <- FunSets::{closure} <- FunSets::contains -> PHPUnit_Framework_Assert::assertFalse -> PHPUnit_Framework_Assert::isFalse -> {closure} -> main <- main <- {closure} <- PHPUnit_Framework_Assert::isFalse -> PHPUnit_Framework_Assert::assertThat -> PHPUnit_Framework_Constraint::count <- PHPUnit_Framework_Constraint::count -> PHPUnit_Framework_Constraint::evaluate -> PHPUnit_Framework_Constraint_IsFalse::matches <- PHPUnit_Framework_Constraint_IsFalse::matches <- PHPUnit_Framework_Constraint::evaluate <- PHPUnit_Framework_Assert::assertThat <- PHPUnit_Framework_Assert::assertFalse <- FunSetsTest::testUnionContainsAllElements ... Time: 1.85 seconds, Memory: 3.75Mb OK (9 tests, 23 assertions) The periods correspond to the successful tests before and after (and from) the test I was tracing. You can see the function entry ("->") and return ("<-") points. Cross checking with the testUnionContainsAllElements() source code confirms the two singletonSet() calls, one union() call, two assertTrue() calls and finally an assertFalse() call. These assertions have a contains() call as a parameter, so contains() is called before the PHPUnit assertion functions are run. You can see contains() being called recursively, and how the closures are invoked. If you want to focus on the application logic and suppress the PHPUnit function trace, you could turn off tracing when assertions are being checked by adding D clauses checking the entry and exit of assertFalse() and assertTrue(). But if you want to see all of PHPUnit's code flow, you can modify the functree.d code that sets and unsets self-follow, and instead change it to toggle the variable in request-startup and request-shutdown probes: php$target:::request-startup { self->follow = 1 } php$target:::request-shutdown { self->follow = 0 } Be prepared for a large amount of output!

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• Evaluating Solutions to Manage Product Compliance? Don't Wait Much Longer

  - by Kerrie Foy

  Depending on severity, product compliance issues can cause all sorts of problems from run-away budgets to business closures. But effective policies and safeguards can create a strong foundation for innovation, productivity, market penetration and competitive advantage. If you’ve been putting off a systematic approach to product compliance, it is time to reconsider that decision, or indecision. Why now?  No matter what industry, companies face a litany of worldwide and regional regulations that require proof of product compliance and environmental friendliness for market access.  For example, Restriction of Hazardous Substances (RoHS) is a regulation that restricts the use of six dangerous materials used in the manufacture of electronic and electrical equipment.  ROHS was originally adopted by the European Union in 2003 for implementation in 2006, and it has evolved over time through various regional versions for North America, China, Japan, Korea, Norway and Turkey.  In addition, the RoHS directive allowed for material exemptions used in Medical Devices, but that exemption ends in 2014.   Additional regulations worth watching are the Battery Directive, Waste Electrical and Electronic Equipment (WEEE), and Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) directives.  Additional evolving regulations are coming from governing bodies like the Food and Drug Administration (FDA) and the International Organization for Standardization (ISO). Corporate sustainability initiatives are also gaining urgency and influencing product design. In a survey of 405 corporations in the Global 500 by Carbon Disclosure Project, co-written by PwC (CDP Global 500 Climate Change Report 2012 entitled Business Resilience in an Uncertain, Resource-Constrained World), 48% of the respondents indicated they saw potential to create new products and business services as a response to climate change. Just 21% reported a dedicated budget for the research. However, the report goes on to explain that those few companies are winning over new customers and driving additional profits by exploiting their abilities to adapt to environmental needs. The article cites Dell as an example – Dell has invested in research to develop new products designed to reduce its customers’ emissions by more than 10 million metric tons of CO2e per year. This reduction in emissions should save Dell’s customers over $1billion per year as a result! Over time we expect to see many additional companies prove that eco-design provides marketplace benefits through differentiation and direct customer value. How do you meet compliance requirements and also successfully invest in eco-friendly designs? No doubt companies struggle to answer this question. After all, the journey to get there may involve transforming business models, go-to-market strategies, supply networks, quality assurance policies and compliance processes per the rapidly evolving global and regional directives. There may be limited executive focus on the initiative, inability to quantify noncompliance, or not enough resources to justify investment. To make things even more difficult to address, compliance responsibility can be a passionate topic within an organization, making the prospect of change on an enterprise scale problematic and time-consuming. Without a single source of truth for product data and without proper processes in place, ensuring product compliance burgeons into a crushing task that is cost-prohibitive and overwhelming to an organization. With all the overhead, certain markets or demographics become simply inaccessible. Therefore, the risk to consumer goodwill and satisfaction, revenue, business continuity, and market potential is too great not to solve the compliance challenge. Companies are beginning to adapt and even thrive in today’s highly regulated and transparent environment by implementing systematic approaches to product compliance that are more than functional bandages but revenue-generating engines. Consider partnering with Oracle to help you address your compliance needs. Many of the world’s most innovative leaders and pioneers are leveraging Oracle’s Agile Product Lifecycle Management (PLM) portfolio of enterprise applications to manage the product value chain, centralize product data, automate processes, and launch more eco-friendly products to market faster.   Particularly, the Agile Product Governance & Compliance (PG&C) solution provides out-of-the-box functionality to integrate actionable regulatory information into the enterprise product record from the ideation to the disposal/recycling phase. Agile PG&C makes it possible to efficiently manage compliance per corporate green initiatives as well as regional and global directives. Options are critical, but so is ease-of-use. Anyone who’s grappled with compliance policy knows legal interpretation plays a major role in determining how an organization responds to regulation. Agile PG&C gives you the freedom to configure product compliance per your needs, while maintaining rigorous control over the product record in an easy-to-use interface that facilitates adoption efforts. It allows you to assign regulations as specifications for a part or BOM roll-up. Each specification has a threshold value that alerts you to a non-compliance issue if the threshold value is exceeded. Set however many regulations as specifications you need to make sure a product can be sold in your target countries. Another option is to implement like one of our leading consumer electronics customers and define your own “catch-all” specification to ensure compliance in all markets. You can give your suppliers secure access to enter their component data or integrate a third party’s data. With Agile PG&C you are able to design compliance earlier into your products to reduce cost and improve quality downstream when stakes are higher. Agile PG&C is a comprehensive solution that makes product compliance more reliable and efficient. Throughout product lifecycles, use the solution to support full material disclosures, efficiently manage declarations with your suppliers, feed compliance data into a corrective action if a product must be changed, and swiftly satisfy audits by showing all due diligence tracked in one solution. Given the compounding regulation and consumer focus on urgent environmental issues, now is the time to act. Implementing an enterprise, systematic approach to product compliance is a competitive investment. From the start, Agile Product Governance & Compliance enables companies to confidently design for compliance and sustainability, reduce the cost of compliance, minimize the risk of business interruption, deliver responsible products, and inspire new innovation.  Don’t wait any longer! To find out more about Agile Product Governance & Compliance download the data sheet, contact your sales representative, or call Oracle at 1-800-633-0738. Many thanks to Shane Goodwin, Senior Manager, Oracle Agile PLM Product Management, for contributions to this article. 

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• Pluralsight Meet the Author Podcast on Structuring JavaScript Code

  - by dwahlin

  I had the opportunity to talk with Fritz Onion from Pluralsight about one of my recent courses titled Structuring JavaScript Code for one of their Meet the Author podcasts. We talked about why JavaScript patterns are important for building more re-useable and maintainable apps, pros and cons of different patterns, and how to go about picking a pattern as a project is started. The course provides a solid walk-through of converting what I call “Function Spaghetti Code” into more modular code that’s easier to maintain, more re-useable, and less susceptible to naming conflicts. Patterns covered in the course include the Prototype Pattern, Revealing Module Pattern, and Revealing Prototype Pattern along with several other tips and techniques that can be used. Meet the Author:  Dan Wahlin on Structuring JavaScript Code   The transcript from the podcast is shown below: [Fritz]  Hello, this is Fritz Onion with another Pluralsight author interview. Today we’re talking with Dan Wahlin about his new course, Structuring JavaScript Code. Hi, Dan, it’s good to have you with us today. [Dan]  Thanks for having me, Fritz. [Fritz]  So, Dan, your new course, which came out in December of 2011 called Structuring JavaScript Code, goes into several patterns of usage in JavaScript as well as ways of organizing your code and what struck me about it was all the different techniques you described for encapsulating your code. I was wondering if you could give us just a little insight into what your motivation was for creating this course and sort of why you decided to write it and record it. [Dan]  Sure. So, I got started with JavaScript back in the mid 90s. In fact, back in the days when browsers that most people haven’t heard of were out and we had JavaScript but it wasn’t great. I was on a project in the late 90s that was heavy, heavy JavaScript and we pretty much did what I call in the course function spaghetti code where you just have function after function, there’s no rhyme or reason to how those functions are structured, they just kind of flow and it’s a little bit hard to do maintenance on it, you really don’t get a lot of reuse as far as from an object perspective. And so coming from an object-oriented background in JAVA and C#, I wanted to put something together that highlighted kind of the new way if you will of writing JavaScript because most people start out just writing functions and there’s nothing with that, it works, but it’s definitely not a real reusable solution. So the course is really all about how to move from just kind of function after function after function to the world of more encapsulated code and more reusable and hopefully better maintenance in the process. [Fritz]  So I am sure a lot of people have had similar experiences with their JavaScript code and will be looking forward to seeing what types of patterns you’ve put forth. Now, a couple I noticed in your course one is you start off with the prototype pattern. Do you want to describe sort of what problem that solves and how you go about using it within JavaScript? [Dan]  Sure. So, the patterns that are covered such as the prototype pattern and the revealing module pattern just as two examples, you know, show these kind of three things that I harp on throughout the course of encapsulation, better maintenance, reuse, those types of things. The prototype pattern specifically though has a couple kind of pros over some of the other patterns and that is the ability to extend your code without touching source code and what I mean by that is let’s say you’re writing a library that you know either other teammates or other people just out there on the Internet in general are going to be using. With the prototype pattern, you can actually write your code in such a way that we’re leveraging the JavaScript property and by doing that now you can extend my code that I wrote without touching my source code script or you can even override my code and perform some new functionality. Again, without touching my code.  And so you get kind of the benefit of the almost like inheritance or overriding in object oriented languages with this prototype pattern and it makes it kind of attractive that way definitely from a maintenance standpoint because, you know, you don’t want to modify a script I wrote because I might roll out version 2 and now you’d have to track where you change things and it gets a little tricky. So with this you just override those pieces or extend them and get that functionality and that’s kind of some of the benefits that that pattern offers out of the box. [Fritz]  And then the revealing module pattern, how does that differ from the prototype pattern and what problem does that solve differently? [Dan]  Yeah, so the prototype pattern and there’s another one that’s kind of really closely lined with revealing module pattern called the revealing prototype pattern and it also uses the prototype key word but it’s very similar to the one you just asked about the revealing module pattern. [Fritz]  Okay. [Dan]  This is a really popular one out there. In fact, we did a project for Microsoft that was very, very heavy JavaScript. It was an HMTL5 jQuery type app and we use this pattern for most of the structure if you will for the JavaScript code and what it does in a nutshell is allows you to get that encapsulation so you have really a single function wrapper that wraps all your other child functions but it gives you the ability to do public versus private members and this is kind of a sort of debate out there on the web. Some people feel that all JavaScript code should just be directly accessible and others kind of like to be able to hide their, truly their private stuff and a lot of people do that. You just put an underscore in front of your field or your variable name or your function name and that kind of is the defacto way to say hey, this is private. With the revealing module pattern you can do the equivalent of what objective oriented languages do and actually have private members that you literally can’t get to as an external consumer of the JavaScript code and then you can expose only those members that you want to be public. Now, you don’t get the benefit though of the prototype feature, which is I can’t easily extend the revealing module pattern type code if you don’t like something I’m doing, chances are you’re probably going to have to tweak my code to fix that because we’re not leveraging prototyping but in situations where you’re writing apps that are very specific to a given target app, you know, it’s not a library, it’s not going to be used in other apps all over the place, it’s a pattern I actually like a lot, it’s very simple to get going and then if you do like that public/private feature, it’s available to you. [Fritz]  Yeah, that’s interesting. So it’s almost, you can either go private by convention just by using a standard naming convention or you can actually enforce it by using the prototype pattern. [Dan]  Yeah, that’s exactly right. [Fritz]  So one of the things that I know I run across in JavaScript and I’m curious to get your take on is we do have all these different techniques of encapsulation and each one is really quite different when you’re using closures versus simply, you know, referencing member variables and adding them to your objects that the syntax changes with each pattern and the usage changes. So what would you recommend for people starting out in a brand new JavaScript project? Should they all sort of decide beforehand on what patterns they’re going to stick to or do you change it based on what part of the library you’re working on? I know that’s one of the points of confusion in this space. [Dan]  Yeah, it’s a great question. In fact, I just had a company ask me about that. So which one do I pick and, of course, there’s not one answer fits all. [Fritz]  Right. [Dan]  So it really depends what you just said is absolutely in my opinion correct, which is I think as a, especially if you’re on a team or even if you’re just an individual a team of one, you should go through and pick out which pattern for this particular project you think is best. Now if it were me, here’s kind of the way I think of it. If I were writing a let’s say base library that several web apps are going to use or even one, but I know that there’s going to be some pieces that I’m not really sure on right now as I’m writing I and I know people might want to hook in that and have some better extension points, then I would look at either the prototype pattern or the revealing prototype. Now, really just a real quick summation between the two the revealing prototype also gives you that public/private stuff like the revealing module pattern does whereas the prototype pattern does not but both of the prototype patterns do give you the benefit of that extension or that hook capability. So, if I were writing a library that I need people to override things or I’m not even sure what I need them to override, I want them to have that option, I’d probably pick a prototype, one of the prototype patterns. If I’m writing some code that is very unique to the app and it’s kind of a one off for this app which is what I think a lot of people are kind of in that mode as writing custom apps for customers, then my personal preference is the revealing module pattern you could always go with the module pattern as well which is very close but I think the revealing module patterns a little bit cleaner and we go through that in the course and explain kind of the syntax there and the differences. [Fritz]  Great, that makes a lot of sense. [Fritz]  I appreciate you taking the time, Dan, and I hope everyone takes a chance to look at your course and sort of make these decisions for themselves in their next JavaScript project. Dan’s course is, Structuring JavaScript Code and it’s available now in the Pluralsight Library. So, thank you very much, Dan. [Dan]  Thanks for having me again.

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• Exam 70-480 Study Material: Programming in HTML5 with JavaScript and CSS3

  - by Stacy Vicknair

  Here’s a list of sources of information for the different elements that comprise the 70-480 exam: General Resources http://www.w3schools.com (As pointed out in David Pallmann’s blog some of this content is unverified, but it is a decent source of information. For more about when it isn’t decent, see http://www.w3fools.com ) http://www.bloggedbychris.com/2012/09/19/microsoft-exam-70-480-study-guide/ (A guy who did a lot of what I did already, sadly I found this halfway through finishing my resources list. This list is expertly put together so I would recommend checking it out.) http://davidpallmann.blogspot.com/2012/08/microsoft-certification-exam-70-480.html http://pluralsight.com/training/Courses (Yes, this isn’t free, but if you look at the course listing there is an entire section on HTML5, CSS3 and Javascript. You can always try the trial!)   Some of the links I put below will overlap with the other resources above, but I tried to find explanations that looked beneficial to me on links outside those already mentioned.   Test Breakdown Implement and Manipulate Document Structures and Objects (24%) Create the document structure. o This objective may include but is not limited to: structure the UI by using semantic markup, including for search engines and screen readers (Section, Article, Nav, Header, Footer, and Aside); create a layout container in HTML http://www.w3schools.com/html/html5_new_elements.asp   Write code that interacts with UI controls. o This objective may include but is not limited to: programmatically add and modify HTML elements; implement media controls; implement HTML5 canvas and SVG graphics http://www.w3schools.com/html/html5_canvas.asp http://www.w3schools.com/html/html5_svg.asp   Apply styling to HTML elements programmatically. o This objective may include but is not limited to: change the location of an element; apply a transform; show and hide elements   Implement HTML5 APIs. o This objective may include but is not limited to: implement storage APIs, AppCache API, and Geolocation API http://www.w3schools.com/html/html5_geolocation.asp http://www.w3schools.com/html/html5_webstorage.asp http://www.w3schools.com/html/html5_app_cache.asp   Establish the scope of objects and variables. o This objective may include but is not limited to: define the lifetime of variables; keep objects out of the global namespace; use the “this” keyword to reference an object that fired an event; scope variables locally and globally http://robertnyman.com/2008/10/09/explaining-javascript-scope-and-closures/ http://www.quirksmode.org/js/this.html   Create and implement objects and methods. o This objective may include but is not limited to: implement native objects; create custom objects and custom properties for native objects using prototypes and functions; inherit from an object; implement native methods and create custom methods http://www.javascriptkit.com/javatutors/object.shtml http://www.crockford.com/javascript/inheritance.html http://stackoverflow.com/questions/1635116/javascript-class-method-vs-class-prototype-method http://www.javascriptkit.com/javatutors/proto.shtml     Implement Program Flow (25%) Implement program flow. o This objective may include but is not limited to: iterate across collections and array items; manage program decisions by using switch statements, if/then, and operators; evaluate expressions http://www.javascriptkit.com/jsref/looping.shtml http://www.javascriptkit.com/javatutors/varshort.shtml http://www.javascriptkit.com/javatutors/switch.shtml   Raise and handle an event. o This objective may include but is not limited to: handle common events exposed by DOM (OnBlur, OnFocus, OnClick); declare and handle bubbled events; handle an event by using an anonymous function http://dev.w3.org/2006/webapi/DOM-Level-3-Events/html/DOM3-Events.html http://javascript.info/tutorial/bubbling-and-capturing   Implement exception handling. o This objective may include but is not limited to: set and respond to error codes; throw an exception; request for null checks; implement try-catch-finally blocks http://www.javascriptkit.com/javatutors/trycatch.shtml   Implement a callback. o This objective may include but is not limited to: receive messages from the HTML5 WebSocket API; use jQuery to make an AJAX call; wire up an event; implement a callback by using anonymous functions; handle the “this” pointer http://www.w3.org/TR/2011/WD-websockets-20110419/ http://www.html5rocks.com/en/tutorials/websockets/basics/ http://api.jquery.com/jQuery.ajax/   Create a web worker process. o This objective may include but is not limited to: start and stop a web worker; pass data to a web worker; configure timeouts and intervals on the web worker; register an event listener for the web worker; limitations of a web worker https://developer.mozilla.org/en-US/docs/DOM/Using_web_workers http://www.html5rocks.com/en/tutorials/workers/basics/   Access and Secure Data (26%) Validate user input by using HTML5 elements. o This objective may include but is not limited to: choose the appropriate controls based on requirements; implement HTML input types and content attributes (for example, required) to collect user input http://diveintohtml5.info/forms.html   Validate user input by using JavaScript. o This objective may include but is not limited to: evaluate a regular expression to validate the input format; validate that you are getting the right kind of data type by using built-in functions; prevent code injection http://www.regular-expressions.info/javascript.html http://msdn.microsoft.com/en-us/library/66ztdbe6(v=vs.94).aspx https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Operators/typeof http://blog.stackoverflow.com/2008/06/safe-html-and-xss/ http://stackoverflow.com/questions/942011/how-to-prevent-javascript-injection-attacks-within-user-generated-html   Consume data. o This objective may include but is not limited to: consume JSON and XML data; retrieve data by using web services; load data or get data from other sources by using XMLHTTPRequest http://www.erichynds.com/jquery/working-with-xml-jquery-and-javascript/ http://www.webdevstuff.com/86/javascript-xmlhttprequest-object.html http://www.json.org/ http://stackoverflow.com/questions/4935632/how-to-parse-json-in-javascript   Serialize, deserialize, and transmit data. o This objective may include but is not limited to: binary data; text data (JSON, XML); implement the jQuery serialize method; Form.Submit; parse data; send data by using XMLHTTPRequest; sanitize input by using URI/form encoding http://api.jquery.com/serialize/ http://www.javascript-coder.com/javascript-form/javascript-form-submit.phtml http://stackoverflow.com/questions/327685/is-there-a-way-to-read-binary-data-into-javascript https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/encodeURI     Use CSS3 in Applications (25%) Style HTML text properties. o This objective may include but is not limited to: apply styles to text appearance (color, bold, italics); apply styles to text font (WOFF and @font-face, size); apply styles to text alignment, spacing, and indentation; apply styles to text hyphenation; apply styles for a text drop shadow http://www.w3schools.com/css/css_text.asp http://www.w3schools.com/css/css_font.asp http://nicewebtype.com/notes/2009/10/30/how-to-use-css-font-face/ http://webdesign.about.com/od/beginningcss/p/aacss5text.htm http://www.w3.org/TR/css3-text/ http://www.css3.info/preview/box-shadow/   Style HTML box properties. o This objective may include but is not limited to: apply styles to alter appearance attributes (size, border and rounding border corners, outline, padding, margin); apply styles to alter graphic effects (transparency, opacity, background image, gradients, shadow, clipping); apply styles to establish and change an element’s position (static, relative, absolute, fixed) http://net.tutsplus.com/tutorials/html-css-techniques/10-css3-properties-you-need-to-be-familiar-with/ http://www.w3schools.com/css/css_image_transparency.asp http://www.w3schools.com/cssref/pr_background-image.asp http://ie.microsoft.com/testdrive/graphics/cssgradientbackgroundmaker/default.html http://www.w3.org/TR/CSS21/visufx.html http://www.barelyfitz.com/screencast/html-training/css/positioning/ http://davidwalsh.name/css-fixed-position   Create a flexible content layout. o This objective may include but is not limited to: implement a layout using a flexible box model; implement a layout using multi-column; implement a layout using position floating and exclusions; implement a layout using grid alignment; implement a layout using regions, grouping, and nesting http://www.html5rocks.com/en/tutorials/flexbox/quick/ http://www.css3.info/preview/multi-column-layout/ http://msdn.microsoft.com/en-us/library/ie/hh673558(v=vs.85).aspx http://dev.w3.org/csswg/css3-grid-layout/ http://dev.w3.org/csswg/css3-regions/   Create an animated and adaptive UI. o This objective may include but is not limited to: animate objects by applying CSS transitions; apply 3-D and 2-D transformations; adjust UI based on media queries (device adaptations for output formats, displays, and representations); hide or disable controls http://www.bloggedbychris.com/2012/09/19/microsoft-exam-70-480-study-guide/   Find elements by using CSS selectors and jQuery. o This objective may include but is not limited to: choose the correct selector to reference an element; define element, style, and attribute selectors; find elements by using pseudo-elements and pseudo-classes (for example, :before, :first-line, :first-letter, :target, :lang, :checked, :first-child) http://www.bloggedbychris.com/2012/09/19/microsoft-exam-70-480-study-guide/   Structure a CSS file by using CSS selectors. o This objective may include but is not limited to: reference elements correctly; implement inheritance; override inheritance by using !important; style an element based on pseudo-elements and pseudo-classes (for example, :before, :first-line, :first-letter, :target, :lang, :checked, :first-child) http://www.bloggedbychris.com/2012/09/19/microsoft-exam-70-480-study-guide/   Technorati Tags: 70-480,CSS3,HTML5,HTML,CSS,JavaScript,Certification

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• Getting Started with TypeScript – Classes, Static Types and Interfaces

  - by dwahlin

  I had the opportunity to speak on different JavaScript topics at DevConnections in Las Vegas this fall and heard a lot of interesting comments about JavaScript as I talked with people. The most frequent comment I heard from people was, “I guess it’s time to start learning JavaScript”. Yep – if you don’t already know JavaScript then it’s time to learn it. As HTML5 becomes more and more popular the amount of JavaScript code written will definitely increase. After all, many of the HTML5 features available in browsers have little to do with “tags” and more to do with JavaScript (web workers, web sockets, canvas, local storage, etc.). As the amount of JavaScript code being used in applications increases, it’s more important than ever to structure the code in a way that’s maintainable and easy to debug. While JavaScript patterns can certainly be used (check out my previous posts on the subject or my course on Pluralsight.com), several alternatives have come onto the scene such as CoffeeScript, Dart and TypeScript. In this post I’ll describe some of the features TypeScript offers and the benefits that they can potentially offer enterprise-scale JavaScript applications. It’s important to note that while TypeScript has several great features, it’s definitely not for everyone or every project especially given how new it is. The goal of this post isn’t to convince you to use TypeScript instead of standard JavaScript….I’m a big fan of JavaScript. Instead, I’ll present several TypeScript features and let you make the decision as to whether TypeScript is a good fit for your applications. TypeScript Overview Here’s the official definition of TypeScript from the http://typescriptlang.org site: “TypeScript is a language for application-scale JavaScript development. TypeScript is a typed superset of JavaScript that compiles to plain JavaScript. Any browser. Any host. Any OS. Open Source.” TypeScript was created by Anders Hejlsberg (the creator of the C# language) and his team at Microsoft. To sum it up, TypeScript is a new language that can be compiled to JavaScript much like alternatives such as CoffeeScript or Dart. It isn’t a stand-alone language that’s completely separate from JavaScript’s roots though. It’s a superset of JavaScript which means that standard JavaScript code can be placed in a TypeScript file (a file with a .ts extension) and used directly. That’s a very important point/feature of the language since it means you can use existing code and frameworks with TypeScript without having to do major code conversions to make it all work. Once a TypeScript file is saved it can be compiled to JavaScript using TypeScript’s tsc.exe compiler tool or by using a variety of editors/tools. TypeScript offers several key features. First, it provides built-in type support meaning that you define variables and function parameters as being “string”, “number”, “bool”, and more to avoid incorrect types being assigned to variables or passed to functions. Second, TypeScript provides a way to write modular code by directly supporting class and module definitions and it even provides support for custom interfaces that can be used to drive consistency. Finally, TypeScript integrates with several different tools such as Visual Studio, Sublime Text, Emacs, and Vi to provide syntax highlighting, code help, build support, and more depending on the editor. Find out more about editor support at http://www.typescriptlang.org/#Download. TypeScript can also be used with existing JavaScript frameworks such as Node.js, jQuery, and others and even catch type issues and provide enhanced code help. Special “declaration” files that have a d.ts extension are available for Node.js, jQuery, and other libraries out-of-the-box. Visit http://typescript.codeplex.com/SourceControl/changeset/view/fe3bc0bfce1f#samples%2fjquery%2fjquery.d.ts for an example of a jQuery TypeScript declaration file that can be used with tools such as Visual Studio 2012 to provide additional code help and ensure that a string isn’t passed to a parameter that expects a number. Although declaration files certainly aren’t required, TypeScript’s support for declaration files makes it easier to catch issues upfront while working with existing libraries such as jQuery. In the future I expect TypeScript declaration files will be released for different HTML5 APIs such as canvas, local storage, and others as well as some of the more popular JavaScript libraries and frameworks. Getting Started with TypeScript To get started learning TypeScript visit the TypeScript Playground available at http://www.typescriptlang.org. Using the playground editor you can experiment with TypeScript code, get code help as you type, and see the JavaScript that TypeScript generates once it’s compiled. Here’s an example of the TypeScript playground in action:   One of the first things that may stand out to you about the code shown above is that classes can be defined in TypeScript. This makes it easy to group related variables and functions into a container which helps tremendously with re-use and maintainability especially in enterprise-scale JavaScript applications. While you can certainly simulate classes using JavaScript patterns (note that ECMAScript 6 will support classes directly), TypeScript makes it quite easy especially if you come from an object-oriented programming background. An example of the Greeter class shown in the TypeScript Playground is shown next: class Greeter { greeting: string; constructor (message: string) { this.greeting = message; } greet() { return "Hello, " + this.greeting; } } Looking through the code you’ll notice that static types can be defined on variables and parameters such as greeting: string, that constructors can be defined, and that functions can be defined such as greet(). The ability to define static types is a key feature of TypeScript (and where its name comes from) that can help identify bugs upfront before even running the code. Many types are supported including primitive types like string, number, bool, undefined, and null as well as object literals and more complex types such as HTMLInputElement (for an <input> tag). Custom types can be defined as well. The JavaScript output by compiling the TypeScript Greeter class (using an editor like Visual Studio, Sublime Text, or the tsc.exe compiler) is shown next: var Greeter = (function () { function Greeter(message) { this.greeting = message; } Greeter.prototype.greet = function () { return "Hello, " + this.greeting; }; return Greeter; })(); Notice that the code is using JavaScript prototyping and closures to simulate a Greeter class in JavaScript. The body of the code is wrapped with a self-invoking function to take the variables and functions out of the global JavaScript scope. This is important feature that helps avoid naming collisions between variables and functions. In cases where you’d like to wrap a class in a naming container (similar to a namespace in C# or a package in Java) you can use TypeScript’s module keyword. The following code shows an example of wrapping an AcmeCorp module around the Greeter class. In order to create a new instance of Greeter the module name must now be used. This can help avoid naming collisions that may occur with the Greeter class.   module AcmeCorp { export class Greeter { greeting: string; constructor (message: string) { this.greeting = message; } greet() { return "Hello, " + this.greeting; } } } var greeter = new AcmeCorp.Greeter("world"); In addition to being able to define custom classes and modules in TypeScript, you can also take advantage of inheritance by using TypeScript’s extends keyword. The following code shows an example of using inheritance to define two report objects:   class Report { name: string; constructor (name: string) { this.name = name; } print() { alert("Report: " + this.name); } } class FinanceReport extends Report { constructor (name: string) { super(name); } print() { alert("Finance Report: " + this.name); } getLineItems() { alert("5 line items"); } } var report = new FinanceReport("Month's Sales"); report.print(); report.getLineItems();   In this example a base Report class is defined that has a variable (name), a constructor that accepts a name parameter of type string, and a function named print(). The FinanceReport class inherits from Report by using TypeScript’s extends keyword. As a result, it automatically has access to the print() function in the base class. In this example the FinanceReport overrides the base class’s print() method and adds its own. The FinanceReport class also forwards the name value it receives in the constructor to the base class using the super() call. TypeScript also supports the creation of custom interfaces when you need to provide consistency across a set of objects. The following code shows an example of an interface named Thing (from the TypeScript samples) and a class named Plane that implements the interface to drive consistency across the app. Notice that the Plane class includes intersect and normal as a result of implementing the interface.   interface Thing { intersect: (ray: Ray) => Intersection; normal: (pos: Vector) => Vector; surface: Surface; } class Plane implements Thing { normal: (pos: Vector) =>Vector; intersect: (ray: Ray) =>Intersection; constructor (norm: Vector, offset: number, public surface: Surface) { this.normal = function (pos: Vector) { return norm; } this.intersect = function (ray: Ray): Intersection { var denom = Vector.dot(norm, ray.dir); if (denom > 0) { return null; } else { var dist = (Vector.dot(norm, ray.start) + offset) / (-denom); return { thing: this, ray: ray, dist: dist }; } } } }   At first glance it doesn’t appear that the surface member is implemented in Plane but it’s actually included automatically due to the public surface: Surface parameter in the constructor. Adding public varName: Type to a constructor automatically adds a typed variable into the class without having to explicitly write the code as with normal and intersect. TypeScript has additional language features but defining static types and creating classes, modules, and interfaces are some of the key features it offers. So is TypeScript right for you and your applications? That’s a not a question that I or anyone else can answer for you. You’ll need to give it a spin to see what you think. In future posts I’ll discuss additional details about TypeScript and how it can be used with enterprise-scale JavaScript applications. In the meantime, I’m in the process of working with John Papa on a new Typescript course for Pluralsight that we hope to have out in December of 2012.

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• Modern Java alternatives

  - by Ralph

  I'm not sure if stackoverflow is the best forum for this discussion. I have been a Java developer for 14 years and have written an enterprise-level (~500,000 line) Swing application that uses most of the standard library APIs. Recently, I have become disappointed with the progress that the language has made to "modernize" itself, and am looking for an alternative for ongoing development. I have considered moving to the .NET platform, but I have issues with using something the only runs well in Windows (I know about Mono, but that is still far behind Microsoft). I also plan on buying a new Macbook Pro as soon as Apple releases their new rumored Arrandale-based machines and want to develop in an environment that will feel "at home" in Unix/Linux. I have considered using Python or Ruby, but the standard Java library is arguably the largest of any modern language. In JVM-based languages, I looked at Groovy, but am disappointed with its performance. Rumor has it that with the soon-to-be released JDK7, with its InvokeDynamic instruction, this will improve, but I don't know how much. Groovy is also not truly a functional language, although it provides closures and some of the "functional" features on collections. It does not embrace immutability. I have narrowed my search down to two JVM-based alternatives: Scala and Clojure. Each has its strengths and weaknesses. I am looking for the stackoverflow readerships' opinions. I am not an expert at either of these languages; I have read 2 1/2 books on Scala and am currently reading Stu Halloway's book on Clojure. Scala is strongly statically typed. I know the dynamic language folks claim that static typing is a crutch for not doing unit testing, but it does provide a mechanism for compile-time location of a whole class of errors. Scala is more concise than Java, but not as much as Clojure. Scala's inter-operation with Java seems to be better than Clojure's, in that most Java operations are easier to do in Scala than in Clojure. For example, I can find no way in Clojure to create a non-static initialization block in a class derived from a Java superclass. For example, I like the Apache commons CLI library for command line argument parsing. In Java and Scala, I can create a new Options object and add Option items to it in an initialization block as follows (Java code): final Options options = new Options() { { addOption(new Option("?", "help", false, "Show this usage information"); // other options } }; I can't figure out how to the same thing in Clojure (except by using (doit...)), although that may reflect my lack of knowledge of the language. Clojure's collections are optimized for immutability. They rarely require copy-on-write semantics. I don't know if Scala's immutable collections are implemented using similar algorithms, but Rich Hickey (Clojure's inventor) goes out of his way to explain how that language's data structures are efficient. Clojure was designed from the beginning for concurrency (as was Scala) and with modern multi-core processors, concurrency takes on more importance, but I occasionally need to write simple non-concurrent utilities, and Scala code probably runs a little faster for these applications since it discourages, but does not prohibit, "simple" mutability. One could argue that one-off utilities do not have to be super-fast, but sometimes they do tasks that take hours or days to complete. I know that there is no right answer to this "question", but I thought I would open it up for discussion. If anyone has a suggestion for another JVM-based language that can be used for enterprise level development, please list it. Also, it is not my intent to start a flame war. Thanks, Ralph

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• Is it bad practice to apply class-based design to JavaScript programs?

  - by helixed

  JavaScript is a prototyped-based language, and yet it has the ability to mimic some of the features of class-based object-oriented languages. For example, JavaScript does not have a concept of public and private members, but through the magic of closures, it's still possible to provide the same functionality. Similarly, method overloading, interfaces, namespaces and abstract classes can all be added in one way or another. Lately, as I've been programming in JavaScript, I've felt like I'm trying to turn it into a class-based language instead of using it in the way it's meant to be used. It seems like I'm trying to force the language to conform to what I'm used to. The following is some JavaScript code I've written recently. It's purpose is to abstract away some of the effort involved in drawing to the HTML5 canvas element. /* Defines the Drawing namespace. */ var Drawing = {}; /* Abstract base which represents an element to be drawn on the screen. @param The graphical context in which this Node is drawn. @param position The position of the center of this Node. */ Drawing.Node = function(context, position) { return { /* The method which performs the actual drawing code for this Node. This method must be overridden in any subclasses of Node. */ draw: function() { throw Exception.MethodNotOverridden; }, /* Returns the graphical context for this Node. @return The graphical context for this Node. */ getContext: function() { return context; }, /* Returns the position of this Node. @return The position of this Node. */ getPosition: function() { return position; }, /* Sets the position of this Node. @param thePosition The position of this Node. */ setPosition: function(thePosition) { position = thePosition; } }; } /* Define the shape namespace. */ var Shape = {}; /* A circle shape implementation of Drawing.Node. @param context The graphical context in which this Circle is drawn. @param position The center of this Circle. @param radius The radius of this circle. @praram color The color of this circle. */ Shape.Circle = function(context, position, radius, color) { //check the parameters if (radius < 0) throw Exception.InvalidArgument; var node = Drawing.Node(context, position); //overload the node drawing method node.draw = function() { var context = this.getContext(); var position = this.getPosition(); context.fillStyle = color; context.beginPath(); context.arc(position.x, position.y, radius, 0, Math.PI*2, true); context.closePath(); context.fill(); } /* Returns the radius of this Circle. @return The radius of this Circle. */ node.getRadius = function() { return radius; }; /* Sets the radius of this Circle. @param theRadius The new radius of this circle. */ node.setRadius = function(theRadius) { radius = theRadius; }; /* Returns the color of this Circle. @return The color of this Circle. */ node.getColor = function() { return color; }; /* Sets the color of this Circle. @param theColor The new color of this Circle. */ node.setColor = function(theColor) { color = theColor; }; //return the node return node; }; The code works exactly like it should for a user of Shape.Circle, but it feels like it's held together with Duct Tape. Can somebody provide some insight on this?

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• Modern alternatives to Java

  - by Ralph

  I have been a Java developer for 14 years and have written an enterprise-level (~500 kloc) Swing application that uses most of the standard library APIs. Recently, I have become disappointed with the progress that the language has made to "modernize" itself, and am looking for an alternative for ongoing development. I have considered moving to the .NET platform, but I have issues with using something the only runs well in Windows (I know about Mono, but that is still far behind Microsoft). I also plan on buying a new Macbook Pro as soon as Apple releases their new rumored Arrandale-based machines and want to develop in an environment that will feel "at home" in Unix/Linux. I have considered using Python or Ruby, but the standard Java library is arguably the largest of any modern language. In JVM-based languages, I looked at Groovy, but am disappointed with its performance. Rumor has it that with the soon-to-be released JDK7, with its InvokeDynamic instruction, this will improve, but I don't know how much. Groovy is also not truly a functional language, although it provides closures and some of the "functional" features on collections. It does not embrace immutability. I have narrowed my search down to two JVM-based alternatives: Scala and Clojure. Each has its strengths and weaknesses. I am looking for opinions. I am not an expert at either of these languages; I have read 2 1/2 books on Scala and am currently reading Stu Halloway's book on Clojure. Scala is strongly statically typed. I know the dynamic language folks claim that static typing is a crutch for not doing unit testing, but it does provide a mechanism for compile-time location of a whole class of errors. Scala is more concise than Java, but not as much as Clojure. Scala's inter-operation with Java seems to be better than Clojure's, in that most Java operations are easier to do in Scala than in Clojure. For example, I can find no way in Clojure to create a non-static initialization block in a class derived from a Java superclass. For example, I like the Apache commons CLI library for command line argument parsing. In Java and Scala, I can create a new Options object and add Option items to it in an initialization block as follows (Java code): final Options options = new Options() { { addOption(new Option("?", "help", false, "Show this usage information"); // other options } }; I can't figure out how to the same thing in Clojure (except by using (doit...)), although that may reflect my lack of knowledge of the language. Clojure's collections are optimized for immutability. They rarely require copy-on-write semantics. I don't know if Scala's immutable collections are implemented using similar algorithms, but Rich Hickey (Clojure's inventor) goes out of his way to explain how that language's data structures are efficient. Clojure was designed from the beginning for concurrency (as was Scala) and with modern multi-core processors, concurrency takes on more importance, but I occasionally need to write simple non-concurrent utilities, and Scala code probably runs a little faster for these applications since it discourages, but does not prohibit, "simple" mutability. One could argue that one-off utilities do not have to be super-fast, but sometimes they do tasks that take hours or days to complete. I know that there is no right answer to this "question", but I thought I would open it up for discussion. Are there other JVM-based languages that can be used for enterprise level development?

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• "Too much recursion" error when loading the same page with a hash

  - by Elliott

  Hi, I have a site w/ an image gallery ("Portfolio") page. There is drop-down navigation that allows a user to view a specific image in the portfolio from any page on the site. The links in the navigation use a hash, and that hash is read and converted into a string of an image filename. The image src attribute on the /portfolio/ page is then swapped out with the new image filename. This works fine if I'm clicking the dropdown link from a page OTHER THAN the /portfolio/ page itself. However if I take the same action from the /portfolio/ page, I get a "too much recursion" error in Firefox. Here's the code: Snippet of the nav markup: <li>Portfolio Category A <ul> <li><a href="/portfolio/#dining-room-table">Dining Room Table</a></li> <li><a href="/portfolio/#bathroom-mirror">Bathroom Mirror</a></li> </ul> </li> JS that reads the hash, converts it to an image filename, and swaps out the image on the page: $(document).ready(function() { if(location.pathname.indexOf("/portfolio/") > -1) { var hash = location.hash; var new_image = hash.replace("#", "")+".jpg"; swapImage(new_image); } }); function swapImage(new_image) { setTimeout(function() { $("img#current-image").attr("src", "/images/portfolio/work/"+new_image); }, 100); } I'm using the setTimeout function because I'm fading out the old image before making the swap, then fading it back in. I initially thought this was the function that was causing the recursion error, but when I remove the setTimeout I still have this problem. Does this have to do with a closure I'm not aware of? I'm pretty green on closures. JS that listens for the click on the nav: $("nav.main li.dropdown li ul li").click(function() { $(this).find("a").click(); $("nav.main").find("ul ul").hide(); $("nav.main li.hover").removeClass("hover"); }); I haven't implemented the fade in/out functionality for the dropdown nav yet, but I have implemented it for Next and Previous arrows, which can also be used to swap out images using the same swapImage function. Here's that code: $("#scroll-arrows a").click(function() { $("#current-image").animate({ opacity: 0 }, 100); var current_image = $("#current-image").attr("src").split("/").pop(); var new_image; var positions = getPositions(current_image); if($(this).is(".right")) { new_image = positions.next_img; } else { new_image = positions.prev_img; } swapImage(new_image); $("#current-image").animate({ opacity: 1 }, 100); return false; }); Here's the error I'm getting in Firefox: too much recursion var ret = handleObj.handler.apply( this, arguments ); jquery.js (line 1936) Thanks for any advice.

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• CodePlex Daily Summary for Sunday, December 09, 2012

  CodePlex Daily Summary for Sunday, December 09, 2012Popular ReleasesMedia Companion: MediaCompanion3.509b: mc_com movie cache unassigned fields bug fixes - votes, movie set & originaltitle were not getting set. No changes to main application from previous release.VidCoder: 1.4.10 Beta: Added progress percent to the title bar/task bar icon. Added MPLS information to Blu-ray titles. Fixed the following display issues in Windows 8: Uncentered text in textbox controls Disabled controls not having gray text making them hard to identify as disabled Drop-down menus having hard-to distinguish white on light-blue text Added more logging to proxy disconnect issues and increased timeout on initial call to help prevent timeouts. Fixed encoding window showing the built-in pre...WPF Application Framework (WAF): WPF Application Framework (WAF) 2.5.0.400: Version 2.5.0.400 (Release): This release contains the source code of the WPF Application Framework (WAF) and the sample applications. Requirements .NET Framework 4.0 (The package contains a solution file for Visual Studio 2010) The unit test projects require Visual Studio 2010 Professional Changelog Legend: [B] Breaking change; [O] Marked member as obsolete Update the documentation. InfoMan: Write the documentation. Other Downloads Downloads OverviewYnote Classic: Ynote Classic version 1.0: Ynote Classic is a text editor made by SS Corporation. It can help you write code by providing you with different codes for creation of html or batch files. You can also create C/C++ /Java files with SS Ynote Classic. Author of Ynote Classic is Samarjeet Singh. Ynote Classic is available with different themes and skins. It can also compile *.bat files into an executable file. It also has a calculator built within it. 1st version released of 6-12-12 by Samarjeet Singh. Please contact on http:...Http Explorer: httpExplorer-1.1: httpExplorer now has the ability to connect to http server via web proxies. The proxy may be explicitly specified by hostname or IP address. Or it may be specified via the Internet Options settings of Windows. You may also specify credentials to pass to the proxy if the proxy requires them. These credentials may be NTLM or basic authentication (clear text username and password).Bee OPOA Platform: Bee OPOA Demo V1.0.001: Initial version.Microsoft Ajax Minifier: Microsoft Ajax Minifier 4.78: Fix for issue #18924 - using -pretty option left in ///#DEBUG blocks. Fix for issue #18980 - bad += optimization caused bug in resulting code. Optimization has been removed pending further review.Selenium PowerShell eXtensions: SePSX 0.4.8: Beta 1: Selenium 2.26, IEDriver 2.26, ChromeDriver 23 Beta 2: Selenium 2.27, IEDriver 2.27, ChromeDriver 23 Beta 3: Selenium 2.27.1, IEDriver 2.27, ChromeDriver 23 This release brings to us several interesting features: ChromeOptions cmdletsThe New-SeChromeOptions, Add-SeChromeArgument, Add-SeChromeExtension and Set-SeChromeBinary cmdlets along with the revisited Start-SeChrome cmdlet give now the full spectrum of possibilities to run a web driver, namely the following seven ways: bare start...Periodic.Net: 0.8: Whats new for Periodic.Net 0.8: New Element Info Dialog New Website MenuItem Minor Bug Fix's, improvements and speed upsHydroDesktop - CUAHSI Hydrologic Information System Desktop Application: 1.5.11 Experimental Release: This is HydroDesktop 1.5.11 Experimental Release We are targeting for a 1.6 Stable Release in Fall 2012. This experimental version has been published for testing. New Features in 1.5 Time Series Data Import Improved performance of table, graph and edit views Support for online sample project packages (sharing data and analyses) More detailed display of time series metadata Improved extension manager (uninstall extensions, choose extension source) Improved attribute table editor (supports fil...Yahoo! UI Library: YUI Compressor for .Net: Version 2.2.0.0 - Epee: New : Web Optimization package! Cleaned up the nuget packages BugFix: minifying lots of files will now be faster because of a recent regression in some code. (We were instantiating something far too many times).DtPad - .NET Framework text editor: DtPad 2.9.0.40: http://dtpad.diariotraduttore.com/files/images/flag-eng.png English + A new built-in editor for the management of CSV files, including the edit of cells, deleting and adding new rows, replacement of delimiter character and much more (issue #1137) + The limit of rows allowed before the decommissioning of their side panel has been raised (new default: 1.000) (issue #1155, only partially solved) + Pressing CTRL+TAB now DtPad opens a screen that shows the list of opened tabs (issue #1143) + Note...AvalonDock: AvalonDock 2.0.1746: Welcome to the new release of AvalonDock 2.0 This release contains a lot (lot) of bug fixes and some great improvements: Views Caching: Content of Documents and Anchorables is no more recreated everytime user move it. Autohide pane opens really fast now. Two new themes Expression (Dark and Light) and Metro (both of them still in experimental stage). If you already use AD 2.0 or plan to integrate it in your future projects, I'm interested in your ideas for new features: http://avalondock...AcDown?????: AcDown????? v4.3.2: ??●AcDown??????????、??、??、???????。????，????，?????????????????????????。???????????Acfun、????(Bilibili)、??、??、YouTube、??、???、??????、SF????、????????????。 ●??????AcPlay?????，??????、????????????????。 ● AcDown??????????????????，????????????????????????????。 ● AcDown???????C#??，????.NET Framework 2.0??。?????"Acfun?????"。 ?? v4.3.2?? ?????????????????? ??Acfun??????? ??Bilibili?????? ??Bilibili???????????? ??Bilibili????????? ??????????????? ???? ??Bilibili??????? ????32??64? Windows XP/...ExtJS based ASP.NET 2.0 Controls: FineUI v3.2.2: ??FineUI ?? ExtJS ??? ASP.NET 2.0 ???。 FineUI??? ?? No JavaScript，No CSS，No UpdatePanel，No ViewState，No WebServices ???????。 ?????? IE 7.0、Firefox 3.6、Chrome 3.0、Opera 10.5、Safari 3.0+ ???? Apache License 2.0 (Apache) ???? ??：http://fineui.com/bbs/ ??：http://fineui.com/demo/ ??：http://fineui.com/doc/ ??：http://fineui.codeplex.com/ ???? +2012-12-03 v3.2.2 -?????????????，?????button/button_menu.aspx（????）。 +?Window????Plain??；?ToolbarPosition??Footer??；?????FooterBarAlign??。 -????win...Player Framework by Microsoft: Player Framework for Windows Phone 8: This is a brand new version of the Player Framework for Windows Phone, available exclusively for Windows Phone 8, and now based upon the Player Framework for Windows 8. While this new version is not backward compatible with Windows Phone 7 (get that http://smf.codeplex.com/releases/view/88970), it does offer the same great feature set plus dozens of new features such as advertising, localization support, and improved skinning. Click here for more information about what's new in the Windows P...SSH.NET Library: 2012.12.3: New feature(s): + SynchronizeDirectoriesQuest: Quest 5.3 Beta: New features in Quest 5.3 include: Grid-based map (sponsored by Phillip Zolla) Changable POV (sponsored by Phillip Zolla) Game log (sponsored by Phillip Zolla) Customisable object link colour (sponsored by Phillip Zolla) More room description options (by James Gregory) More mathematical functions now available to expressions Desktop Player uses the same UI as WebPlayer - this will make it much easier to implement customisation options New sorting functions: ObjectListSort(list,...Chinook Database: Chinook Database 1.4: Chinook Database 1.4 This is a sample database available in multiple formats: SQL scripts for multiple database vendors, embeded database files, and XML format. The Chinook data model is available here. ChinookDatabase1.4_CompleteVersion.zip is a complete package for all supported databases/data sources. There are also packages for each specific data source. Supported Database ServersDB2 EffiProz MySQL Oracle PostgreSQL SQL Server SQL Server Compact SQLite Issues Resolved293...RiP-Ripper & PG-Ripper: RiP-Ripper 2.9.34: changes FIXED: Thanks Function when "Download each post in it's own folder" is disabled FIXED: "PixHub.eu" linksNew ProjectsBaldur's Gate Party Gold Editor - WPF, Windows Forms MVP-VM sample: MVP-VM sample WPF, Windows Forms MVP-VM sampleEGRemote Studio: EGRemote Studio is a gateway application that enables communication between Eventghost and Google's push messaging service.Emptycanvas: Le projet emptycanvas est destiné aux créations de vidéos en images de synthèse ainsi qu'aux conceptions 3D sur ordinateur.eveCIMS - A Corporation Information and Management System for eve online: eveCIMS is a web application for managing a corporation in CCPs Spaceship Game EVE Online. Google Helper: Google HelperHongloumeng: ???RPG????Mobile Projects LFD: Projeto voltado a agrupar funções simples de plataformas moveis.Momra Transfers: This is transfers project for momraMuhammad Tarmizi bin Kamaruddin's simple free software (primary edition) (BETA): Muhammad Tarmizi bin Kamaruddin's simple free software (primary edition) (BETA)Nth Parameter Series: Silverlight Business application to use the concept of extending the double time series used extensivelly in the finance industry.OMR.EasyBackup: Example of easy real time file system backup project.SharePoint - Web Customization Inheritance: This project allows to inherit customizations of a site to is childrens, including master page, theme and logo. Tennis_HDU: TennisHDUTuto Direct3D 11 SDZ: Code source accompagnant le tutoriel disponible sur le Site du Zéro.Visual Studio 2010 Settings Swapper AddIn: Settings swapper makes it simple to have Visual Studio settings apply per file type. For example, maybe you want to have settings for a aspx MVC page be different from a C# file. The project was created in and tested with Visual Studio 2010 and written in C#.Weak Closure Pattern: The weak closures. Creation of the closure behavior that independent from a compiler.??MVC?????????: ??MVC ??????????，??????MVC3、Autofac、Lucene.net 3.0,??Npoi.net，Nhibernate、quartz.net???????，??????????????????????，????????，????

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• Watching setTimeout loops so that only one is running at a time.

  - by DA

  I'm creating a content rotator in jQuery. 5 items total. Item 1 fades in, pauses 10 seconds, fades out, then item 2 fades in. Repeat. Simple enough. Using setTimeout I can call a set of functions that create a loop and will repeat the process indefinitely. I now want to add the ability to interrupt this rotator at any time by clicking on a navigation element to jump directly to one of the content items. I originally started going down the path of pinging a variable constantly (say every half second) that would check to see if a navigation element was clicked and, if so, abandon the loop, then restart the loop based on the item that was clicked. The challenge I ran into was how to actually ping a variable via a timer. The solution is to dive into JavaScript closures...which are a little over my head but definitely something I need to delve into more. However, in the process of that, I came up with an alternative option that actually seems to be better performance-wise (theoretically, at least). I have a sample running here: http://jsbin.com/uxupi/14 (It's using console.log so have fireBug running) Sample script: $(document).ready(function(){ var loopCount = 0; $('p#hello').click(function(){ loopCount++; doThatThing(loopCount); }) function doThatOtherThing(currentLoopCount) { console.log('doThatOtherThing-'+currentLoopCount); if(currentLoopCount==loopCount){ setTimeout(function(){doThatThing(currentLoopCount)},5000) } } function doThatThing(currentLoopCount) { console.log('doThatThing-'+currentLoopCount); if(currentLoopCount==loopCount){ setTimeout(function(){doThatOtherThing(currentLoopCount)},5000); } } }) The logic being that every click of the trigger element will kick off the loop passing into itself a variable equal to the current value of the global variable. That variable gets passed back and forth between the functions in the loop. Each click of the trigger also increments the global variable so that subsequent calls of the loop have a unique local variable. Then, within the loop, before the next step of each loop is called, it checks to see if the variable it has still matches the global variable. If not, it knows that a new loop has already been activated so it just ends the existing loop. Thoughts on this? Valid solution? Better options? Caveats? Dangers? UPDATE: I'm using John's suggestion below via the clearTimeout option. However, I can't quite get it to work. The logic is as such: var slideNumber = 0; var timeout = null; function startLoop(slideNumber) { ...do stuff here to set up the slide based on slideNumber... slideFadeIn() } function continueCheck(){ if (timeout != null) { // cancel the scheduled task. clearTimeout(timeout); timeout = null; return false; }else{ return true; } }; function slideFadeIn() { if (continueCheck){ // a new loop hasn't been called yet so proceed... // fade in the LI $currentListItem.fadeIn(fade, function() { if(multipleFeatures){ timeout = setTimeout(slideFadeOut,display); } }); }; function slideFadeOut() { if (continueLoop){ // a new loop hasn't been called yet so proceed... slideNumber=slideNumber+1; if(slideNumber==features.length) { slideNumber = 0; }; timeout = setTimeout(function(){startLoop(slideNumber)},100); }; startLoop(slideNumber); The above kicks of the looping. I then have navigation items that, when clicked, I want the above loop to stop, then restart with a new beginning slide: $(myNav).click(function(){ clearTimeout(timeout); timeout = null; startLoop(thisItem); }) If I comment out 'startLoop...' from the click event, it, indeed, stops the initial loop. However, if I leave that last line in, it doesn't actually stop the initial loop. Why? What happens is that both loops seem to run in parallel for a period. So, when I click my navigation, clearTimeout is called, which clears it.

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