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  • Performance and Optimization Isn’t Evil

    - by Reed
    Donald Knuth is a fairly amazing guy.  I consider him one of the most influential contributors to computer science of all time.  Unfortunately, most of the time I hear his name, I cringe.  This is because it’s typically somebody quoting a small portion of one of his famous statements on optimization: “premature optimization is the root of all evil.” I mention that this is only a portion of the entire quote, and, as such, I feel that Knuth is being quoted out of context.  Optimization is important.  It is a critical part of every software development effort, and should never be ignored.  A developer who ignores optimization is not a professional.  Every developer should understand optimization – know what to optimize, when to optimize it, and how to think about code in a way that is intelligent and productive from day one. I want to start by discussing my own, personal motivation here.  I recently wrote about a performance issue I ran across, and was slammed by multiple comments and emails that effectively boiled down to: “You’re an idiot.  Premature optimization is the root of all evil.  This doesn’t matter.”  It didn’t matter that I discovered this while measuring in a profiler, and that it was a portion of my code base that can take “many hours to complete.”  Even so, multiple people instantly jump to “it’s premature – it doesn’t matter.” This is a common thread I see.  For example, StackOverflow has many pages of posts with answers that boil down to (mis)quoting Knuth.  In fact, just about any question relating to a performance related issue gets this quote thrown at it immediately – whether it deserves it or not.  That being said, I did receive some positive comments and emails as well.  Many people want to understand how to optimize their code, approaches to take, tools and techniques they can use, and any other advice they can discover. First, lets get back to Knuth – I mentioned before that Knuth is being quoted out of context.  Lets start by looking at the entire quote from his 1974 paper Structured Programming with go to Statements: “We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil. Yet we should not pass up our opportunities in that critical 3%. A good programmer will not be lulled into complacency by such reasoning, he will be wise to look carefully at the critical code; but only after that code has been identified.” Ironically, if you read Knuth’s original paper, this statement was made in the middle of a discussion of how Knuth himself had changed how he approaches optimization.  It was never a statement saying “don’t optimize”, but rather, “optimizing intelligently provides huge advantages.”  His approach had three benefits: “a) it doesn’t take long” … “b) the payoff is real”, c) you can “be less efficient in the other parts of my programs, which therefore are more readable and more easily written and debugged.” Looking at Knuth’s premise here, and reading that section of his paper, really leads to a few observations: Optimization is important  “he will be wise to look carefully at the critical code” Normally, 3% of your code – three lines out of every 100 you write, are “critical code” and will require some optimization: “we should not pass up our opportunities in that critical 3%” Optimization, if done well, should not be time consuming: “it doesn’t take long” Optimization, if done correctly, provides real benefits: “the payoff is real” None of this is new information.  People who care about optimization have been discussing this for years – for example, Rico Mariani’s Designing For Performance (a fantastic article) discusses many of the same issues very intelligently. That being said, many developers seem unable or unwilling to consider optimization.  Many others don’t seem to know where to start.  As such, I’m going to spend some time writing about optimization – what is it, how should we think about it, and what can we do to improve our own code.

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  • Downloading javascript Without Blocking

    - by doug
    The context: My question relates to improving web-page loading performance, and in particular the effect that javascript has on page-loading (resources/elements below the script are blocked from downloading/rendering). This problem is usually avoided/mitigated by placing the scripts at the bottom (eg, just before the tag). The code i am looking at is for web analytics. Placing it at the bottom reduces its accuracy; and because this script has no effect on the page's content, ie, it's not re-writing any part of the page--i want to move it inside the head. Just how to do that without ruining page-loading performance is the crux. From my research, i've found six techniques (w/ support among all or most of the major browsers) for downloading scripts so that they don't block down-page content from loading/rendering: (i) XHR + eval(); (ii) XHR + 'inject'; (iii) download the HTML-wrapped script as in iFrame; (iv) setting the script tag's 'async' flag to 'TRUE' (HTML 5 only); (v) setting the script tag's 'defer' attribute; and (vi) 'Script DOM Element'. It's the last of these i don't understand. The javascript to implement the pattern (vi) is: (function() { var q1 = document.createElement('script'); q1.src = 'http://www.my_site.com/q1.js' document.documentElement.firstChild.appendChild(q1) })(); Seems simple enough: inside this anonymous function, a script element is created, its 'src' element is set to it's location, then the script element is added to the DOM. But while each line is clear, it's still not clear to me how exactly this pattern allows script loading without blocking down-page elements/resources from rendering/loading?

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  • JavaScript local alias pattern

    - by Bertrand Le Roy
    Here’s a little pattern that is fairly common from JavaScript developers but that is not very well known from C# developers or people doing only occasional JavaScript development. In C#, you can use a “using” directive to create aliases of namespaces or bring them to the global scope: namespace Fluent.IO { using System; using System.Collections; using SystemIO = System.IO; In JavaScript, the only scoping construct there is is the function, but it can also be used as a local aliasing device, just like the above using directive: (function($, dv) { $("#foo").doSomething(); var a = new dv("#bar"); })(jQuery, Sys.UI.DataView); This piece of code is making the jQuery object accessible using the $ alias throughout the code that lives inside of the function, without polluting the global scope with another variable. The benefit is even bigger for the dv alias which stands here for Sys.UI.DataView: think of the reduction in file size if you use that one a lot or about how much less you’ll have to type… I’ve taken the habit of putting almost all of my code, even page-specific code, inside one of those closures, not just because it keeps the global scope clean but mostly because of that handy aliasing capability.

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  • Using ASP.NET C# and Javascript

    - by ctck
    I'm looking for the most efficient / standardized way of passing data between client javascript code and C# code behind in an ASP.NET application. Currently ive been using the following methods to achieve this but they all feel a bit like a fudge. The way i pass data from javascript to the C# code behind is by setting hidden asp variables and triggering a postback <asp:HiddenField ID="RandomList" runat="server" /> function SetDataField(data) { document.getElementById('<%=RandomList.ClientID%>').value = data; } Then in C# code i collect the list protected void GetData(object sender, EventArgs e) { var _list = RandomList.value; } Going back the other way i often use either scriptmanager to register a function and pass it data during Page_Load: ScriptManager.RegisterStartupScript(this.GetType(), "Set","get("Test();",true); or i add attributes to controls before a post back or during Initialization / pre rendering stages: Btn.Attributes.Add("onclick", "DisplayMessage("Hello");"); These methods have served me well and do the job. However they just dont feel complete. Is there a more standardized way of passing data between client side markup / javascript and backend code. Ive seen some posts like this one: Injecting JavaScrip : StackOverflow that describe HtmlElement class. Is this something is should look into? Thanks everyone for your time.

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  • Website performance tips?

    - by Michael Schinis
    Im kind of having some troubles with the loading of my website: Here's a link to the website: link It sometimes loads fast, then when you refresh it.. most of the times, it will just keep trying to load images, and keep doing that for a minute or so, and none of the javascript will execute. I have followed most of the tips given by yahoo, except caching, which I couldn't get working properly. Does anyone know how to do proper caching of image and javascript files using htaccess? most of the code I found online won't work. Any advice whatsoever is extremely helpful. Thanks

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  • Interesting links week #6

    - by erwin21
    Below a list of interesting links that I found this week: Frontend: Understanding CSS Selectors Javascript: Breaking the Web with hash-bangs HTML5 Peeks, Pokes and Pointers Development: 10 Points to Take Care While Building Links for SEO View State decoder ASP.NET MVC Performance Tips Other: Things to Remember Before Launching a Website Tips and Tricks On How To Become a Presentation Ninja 10 Ways to Simplify Your Workday Interested in more interesting links follow me at twitter http://twitter.com/erwingriekspoor

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  • How to improve performance of map that loads new overlay images

    - by anthonysomerset
    I have inherited a website to maintain that uses a html map overlaying a real map to link specific countries to specific pages. previously it loaded the default map image, then with some javascript it would change the image src to an image with that particular country in a different colour on mouseover and reset the image source back to the original image on mouse out to make maintenance (adding new countries) easier i made the initial map a background image by utilising some CSS for the div tag, and then created new images for each country which only had that countries hightlight so that the images remain fairly small. this works great but theres one issue which is particularly noticeable on slower internet connections when you hover over a country if you dont have the image file in your browser cache or downloaded it wont load the image unless you hover over another country and then back onto the first country - i guess this is due to the image having to manually be downloaded on first hover. My question: is it possible to force the load of these extra images AFTER the page and all the other assets have finished loading so that this behaviour is all but eliminated? the html code for the MAP is as follows: <div class="gtmap"><img id="Image-Maps_6200909211657061" src="<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png" usemap="#Image-Maps_6200909211657061" alt="We offer Guided Motorcycle Tours all around the world" width="615" height="296" /> <map id="_Image-Maps_6200909211657061" name="Image-Maps_6200909211657061"> <area shape="poly" coords="511,134,532,107,542,113,520,141" href="/guided-motorcycle-tours-japan/" alt="Guided Japan Motorcycle Tours" title="Japan" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-japan.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="252,61,266,58,275,64,262,68" href="/guided-motorcycle-tour.php?iceland-motorcycle-adventure-39" alt="Guided Iceland Motorcycle Tours" title="Iceland" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-iceland.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="587,246,597,256,577,279,568,270" href="/guided-motorcycle-tour.php?new-zealand-south-island-adventure-10" alt="New Zealand Guided Motorcycle Tours" title="New Zealand" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-nz.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="418,133,412,145,412,154,421,178,430,180,430,166,443,154,443,145,438,144,433,142,430,138,431,130,430,129,425,128" href="/guided-motorcycle-tours-india/" alt="India Guided Motorcycle Tours" title="India" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-india.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="460,152,466,149,474,165,470,171,466,161" href="/guided-motorcycle-tours-laos/" alt="Laos Guided Motorcycle Tours" title="Laos" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-laos.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="468,179,475,166,468,152,475,152,482,169" href="/guided-motorcycle-tour.php?indochina-motorcycle-adventure-tour-32" onClick="javascript: pageTracker._trackPageview('/internal-links/guided-tours/map/vietnam');" alt="Vietnam Guided Motorcycle Tours" title="Vietnam" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-viet.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="330,239,337,235,347,226,352,233,351,243,344,250,335,253,327,255,323,249,322,242,323,241" href="/guided-motorcycle-tours-southafrica/" alt="South Africa Guided Motorcycle Tours" title="South Africa" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-sa.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="290,77,293,86,298,96,286,102,285,97,285,89,282,84,282,79" href="/guided-motorcycle-tour.php?great-britain-isle-of-man-scotland-wales-uk-18" alt="United Kingdom" title="United Kingdom Guided Motorcycle Tours" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-uk.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="357,118,368,118,369,126,345,129,338,125,338,117,342,115,348,116" href="/guided-motorcycle-tour.php?explore-turkey-adventure-45" alt="Turkey" title="Turkey Guided Motorcycle Tours" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-turkey.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="206,95,193,101,185,101,178,106,165,111,157,109,147,105,134,103,121,103,107,103,96,103,86,104,81,99,77,91,70,83,62,79,60,72,61,64,59,57,60,51,71,50,83,49,95,50,107,54,117,53,129,47,137,36,148,37,163,38,177,44,187,54,195,60,184,72,191,80,200,87" href="/guided-motorcycle-tours-canada/" alt="Guided Canada Motorcycle Tours" title="Canada" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-canada.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="61,75,60,62,60,55,59,44,51,44,43,43,36,42,28,43,23,48,17,51,15,62,19,74,27,79,19,83,16,93,35,83,43,77,50,75,55,75" href="/guided-motorcycle-tours-alaska/" alt="Guided Alaska Motorcycle Tours" title="Alaska" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-alaska.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="82,101,99,101,133,101,148,105,161,110,172,106,187,100,180,113,171,122,165,131,159,149,147,141,137,140,129,147,120,141,112,138,103,137,93,132,86,122,86,112,86,106" href="/guided-motorcycle-tours-usa/" alt="USA Guided Motorcycle Tours" title="USA" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-usa.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="178,225,180,214,175,208,174,204,178,198,174,193,167,192,157,199,158,204,164,211,167,218" href="/guided-motorcycle-tour.php?peru-machu-picchu-adventure-25" alt="Peru Guided Motorcycle Tours" title="Peru" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-peru.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="172,226,169,239,166,256,166,267,164,279,171,277,174,262,175,250,179,234,180,225,176,224" href="/guided-motorcycle-tours-chile/" alt="Guided Chile Motorcycle Tours" title="Chile" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-chile.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="199,260,194,261,187,265,184,276,183,296,170,292,168,282,174,270,174,257,177,245,180,230,190,228,205,237,199,245" href="/guided-motorcycle-tours-argentina/" alt="Guided Argentina Motorcycle Tours" title="Argentina" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-arg.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> </map> </div> The <?php echo cdnhttpsCheck(); ?> is just a site specific function that gets the correct web domain/url from a config file to load resources from CDN where possible (eg all non HTTPS requests) We are loading Jquery at the bottom of the HTML if anybody wonders why it is missing from the code snippet for reference, the page with the map in question is found here: http://www.motoquest.com/guided-motorcycle-tours/

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  • Gotcha when using JavaScript in ADF Regions

    - by Frank Nimphius
    You use the ADF Faces af:resource tag to add or reference JavaScript on a page. However, adding the af:resource tag to a page fragment my not produce the desired result if the script is added as shown below <?xml version='1.0' encoding='UTF-8'?> <jsp:root xmlns:jsp="http://java.sun.com/JSP/Page" version="2.1" xmlns:af="http://xmlns.oracle.com/adf/faces/rich"> <af:resource type="javascript">   function yourMethod(evt){ ... } </af:resource> Adding scripts to a page fragment like this will see the script added for the first page fragment loaded by an ADF region but not for any subsequent fragment navigated to within the context of task flow navigation. The cause of this problem is caching as the af:resource tag is a JSP element and not a lazy loaded JSF component, which makes it a candidate for caching. To solve the problem, move the af:resource tag into a container component like af:panelFormLayout so the script is added when the component is instantiated and added to the page.  <?xml version='1.0' encoding='UTF-8'?> <jsp:root xmlns:jsp="http://java.sun.com/JSP/Page" version="2.1" xmlns:af="http://xmlns.oracle.com/adf/faces/rich"> <af:panelFormLayout> <af:resource type="javascript">   function yourMethod(evt){ ... } </af:resource> </af:panelFormLayout> Magically this then works and prevents browser caching of the script when using page fragments.

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  • What is the most performant CSS property for transitioning an element?

    - by Ian Kuca
    I'm wondering whether there is a performance difference between using different CSS properties to translate an element. Some properties fit different situations differently. You can translate an element with following properties: transform, top/left/right/bottom and margin-top/left/right/bottom In the case where you do not utilize the transition CSS property for the translation but use some form of a timer (setTimeout, requestAnimationFrame or setImmediate) or raw events, which is the most performant–which is going to make for higher FPS rates?

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  • Why is Javascript used in MongoDB and CouchDB instead of other languages such as Java, C++?

    - by startup007
    I asked this question on SO but was suggested to try here. So here it goes: My understanding of Javascript so far has been that it is a client-side language that capture events and makes a web-page dynamic. But on reading the comparison between MongoDB and CouchDB I noticed that both are using Javascript. This makes me wonder the reason behind the choice of JavaScript over other conventional languages. I guess I am trying to understand the role of JavaScript and its advantages over other languages. Update: I am not asking about the languages / drivers supported by the two databases. The comparison says: Both CouchDB and MongoDB make use of Javascript. CouchDB uses Javascript extensively including in the building of views. MongoDB also supports running arbitrary javascript functions server-side and uses javascript for map/reduce operations. My lack of understanding pertains to why is Javascript being used at all for the backend work. Why is it preferred for building views in CouchDB, or for using map/reduce operations? Why C/C++ or Java were not used? What are the advantages in using Javascript for such back-end work?

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  • javascript select box hanging on second select in ie7

    - by bsandrabr
    I have a drop down select box inside a div. When the user clicks on change, a dropdown box appears next to the change/submit button and the user makes a selection which then updates the db and the selection appears instead of the dropdown. All works fine in IE8 and firefox but in IE7 it allows one selection (there are several identical dropdowns) but the second time a selection is made it hangs on please wait. This is the relevant code <td width=200> <input type="button" onclick="startChanging(this)" value="Change" /></td> <script type="text/javascript"> var selectBox, isEditing = false; var recordvalue; if( window.XMLHttpRequest ) { recordvalue = new XMLHttpRequest(); } else if( window.ActiveXObject ) { try { recordvalue = new ActiveXObject('Microsoft.XMLHTTP'); } catch(e) {} } window.onload = function () { selectBox = document.getElementById('changer'); selectBox.id = ''; selectBox.parentNode.removeChild(selectBox); }; function startChanging(whatButton) { if( isEditing && isEditing != whatButton ) { return; } //no editing of other entries if( isEditing == whatButton ) { changeSelect(whatButton); return; } //this time, act as "submit" isEditing = whatButton; whatButton.value = 'Submit'; var theRow = whatButton.parentNode.parentNode; var stateCell = theRow.cells[3]; //the cell that says "present" stateCell.className = 'editing'; //so you can use CSS to remove the background colour stateCell.replaceChild(selectBox,stateCell.firstChild); //PRESENT is replaced with the select input selectBox.selectedIndex = 0; } function changeSelect(whatButton) { isEditing = true; //don't allow it to be clicked until submission is complete whatButton.value = 'Change'; var stateCell = selectBox.parentNode; var theRow = stateCell.parentNode; var editid = theRow.cells[0].firstChild.firstChild.nodeValue; //text inside the first cell var value = selectBox.firstChild.options[selectBox.firstChild.selectedIndex].value; //the option they chose selectBox.parentNode.replaceChild(document.createTextNode('Please wait...'),selectBox); if( !recordvalue ) { //allow fallback to basic HTTP location.href = 'getupdate.php?id='+editid+'&newvalue='+value; } else { recordvalue.onreadystatechange = function () { if( recordvalue.readyState != 4 ) { return; } if( recordvalue.status >= 300 ) { alert('An error occurred when trying to update'); } isEditing = false; newState = recordvalue.responseText.split("|"); stateCell.className = newState[0]; stateCell.firstChild.nodeValue = newState[1] || 'Server response was not correct'; }; recordvalue.open('GET', "getupdate.php?id="+editid+"&newvalue="+value, true); recordvalue.send(null); } } </script> If anyone has any idea why this is happening I'd be very grateful

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  • Javascript not getting keyDown input

    - by William
    For some reason my code just isn't wanting to fire off any kind of OnKeyDown event. I don't know why. Can anyone tell me what I'm doing wrong? <!DOCTYPE html> <html lang="en"> <head> <title>Canvas test</title> <meta charset="utf-8" /> <link href="/bms/style.css" rel="stylesheet" /> <style> body { text-align: center; background-color: #000000;} canvas{ background-color: #ffffff;} </style> <script type="text/javascript"> var x = 50; var y = 250; var speed = 5; function controls(event){ if(!e){ //for IE e = window.event; } if(e.keyCode==37){//keyCode 37 is left arrow x -= speed; } if(e.keyCode==39){ //keyCode 39 is right arrow x += speed; } if(e.keyCode==38){//keyCode 37 is up arrow y -= speed; } if(e.keyCode==40){ //keyCode 39 is down arrow y += speed; } } function update(){ document.onkeydown="controls(event);"; draw(); } function draw(){ var canvas = document.getElementById('screen1'); if (canvas.getContext){ var ctx = canvas.getContext('2d'); ctx.fillStyle = 'rgba(255,255,255,0.5)'; ctx.fillRect(0,0,500,500); ctx.fillStyle = 'rgb(236,138,68)'; ctx.fillRect(x,y,25,25); } } setInterval('update();', 1000/60); </script> </head> <body> <canvas id="screen1" width="500" height="500"></canvas> </body> </html>

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  • Javascript self contained sandbox events and client side stack

    - by amnon
    I'm in the process of moving a JSF heavy web application to a REST and mainly JS module application . I've watched "scalable javascript application architecture" by Nicholas Zakas on yui theater (excellent video) and implemented much of the talk with good success but i have some questions : I found the lecture a little confusing in regards to the relationship between modules and sandboxes , on one had to my understanding modules should not be effected by something happening outside of their sandbox and this is why they publish events via the sandbox (and not via the core as they do access the core for hiding base libary) but each module in the application gets a new sandbox ? , shouldn't the sandbox limit events to the modoules using it ? or should events be published cross page ? e.g. : if i have two editable tables but i want to contain each one in a different sandbox and it's events effect only the modules inside that sandbox something like messabe box per table which is a different module/widget how can i do that with sandbox per module , ofcourse i can prefix the events with the moduleid but that creates coupling that i want to avoid ... and i don't want to package modules toghter as one module per combination as i already have 6-7 modules ? while i can hide the base library for small things like id selector etc.. i would still like to use the base library for module dependencies and resource loading and use something like yui loader or dojo.require so in fact i'm hiding the base library but the modules themself are defined and loaded by the base library ... seems a little strange to me libraries don't return simple js objects but usualy wrap them e.g. : u can do something like $$('.classname').each(.. which cleans the code alot , it makes no sense to wrap the base and then in the module create a dependency for the base library by executing .each but not using those features makes a lot of code written which can be left out ... and implemnting that functionality is very bug prone does anyonen have any experience with building a front side stack of this order ? how easy is it to change a base library and/or have modules from different libraries , using yui datatable but doing form validation with dojo ... ? some what of a combination of 2+4 if u choose to do something like i said and load dojo form validation widgets for inputs via yui loader would that mean dojocore is a module and the form module is dependant on it ? Thanks .

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  • SQLAuthority News – Microsoft SQL Server 2005/2008 Query Optimization & Performance Tuning Training

    - by pinaldave
    Last 3 days to register for the courses. This is one time offer with big discount. The deadline for the course registration is 5th May, 2010. There are two different courses are offered by Solid Quality Mentors 1) Microsoft SQL Server 2005/2008 Query Optimization & Performance Tuning – Pinal Dave Date: May 12-14, 2010 Price: Rs. 14,000/person for 3 days Discount Code: ‘SQLAuthority.com’ Effective Price: Rs. 11,000/person for 3 days 2) SharePoint 2010 – Joy Rathnayake Date: May 10-11, 2010 Price: Rs. 11,000/person for 3 days Discount Code: ‘SQLAuthority.com’ Effective Price: Rs. 8,000/person for 2 days Download the complete PDF brochure. To register, either send an email to [email protected] or call +91 95940 43399. Feel free to drop me an email at pinal “at” SQLAuthority.com for any additional information and clarification. Training Venue: Abridge Solutions, #90/B/C/3/1, Ganesh GHR & MSY Plaza, Vittalrao Nagar, Near Image Hospital, Madhapur, Hyderabad – 500 081. Additionally there is special program of SolidQ India Insider. This is only available to first few registrants of the courses only. Read more details about the course here. Read my TechEd India 2010 experience here. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQL Training, SQLAuthority News, T SQL, Technology

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  • SQLAuthority News – SQL Server Performance Series Hyderabad / Pune – Nov/Dec 2010

    - by pinaldave
    Just a quick note that SQL Server Performance Tuning and Optimizations Seminar series which I am offering at Hyderabad and Pune are almost all sold out. Read the details of the earlier successful seminar conducted at Colombo, Sri Lanka over here. Hyderabad Nov 27-28, 2010 (Last 3 Seats Left) Best Western Amrutha Castle 5-9-16, Opp. Secretriat, Saifabad, Khairatabad Hyderabad, Andhra Pradesh Pune Dec 04-05, 2010 (Last 6 Seats Left) Location TBA as we are looking for larger capacity room. I promise that this is going to be great fun as this sessions are very different then any usual sessions you have ever attended. This sessions are absolutely interactive and all the attendees will feel part of the event. As larger group are not convenient we are limited this seminars to very small group of people. This way attendees can go to instructors any time and feel connected. This 2-day seminar will cover the best of the best concepts and practices from popular courses offered by Solid Quality Mentors. Instead of learning theory only, the seminar focuses on providing real world experience by using demos and scenarios derived from customer engagements. The seminar is uniquely structured and well-thought-out. Sessions are discussion- based and are designed to be an interactive gateway between the instructor and the participants for an optimal learning experience. The seminar is intended to be immersion-based where participants will have plenty of opportunities to get deeply involved in the concepts presented by the instructor. Agenda of the event To join the seminars drop me an email. My email address is pinal “at” SQLAuthority.com and IndiaInfo “at” SolidQ.com. If you specify SQLAuthority.com in Title, you will avail special discount in overall rates on specified price. Yes, a sure 20% I promise. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: About Me, Pinal Dave, SQL, SQL Authority, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology

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  • June 22-24, 2010 in London City Level 400 SQL Server Performance Monitoring & Tuning Workshop

    - by sqlworkshops
    We are organizing the “3 Day Level 400 SQL Server Performance Monitoring & Tuning Workshop” for the 1st time in London City during June 22-24, 2010.Agenda is located @ www.sqlworkshops.com/workshops & you can register @ www.sqlworkshops.com/ruk. Charges: £ 1800 (5% discount for those who register before 21st May, £ 1710).In this 3 Day Level 400 hands-on workshop, unlike short SQLBits sessions, we go deeper on the tuning topics. Not sure if this will be a good use of your time & money? Watch our webcasts @ www.sqlworkshops.com/webcasts.We are trying to balance these commercial offerings with our free community contributions. Financially: These workshops are essential for us to stay in business!Feedback from Finland workshop posted by Jukka, Wärtsilä Oyj on February 23, 2010 to the LinkedIn SQL Server User Group Finland (more feedbacks @ www.sqlworkshops.com/feedbacks):Just want to start this thread and give some feedback on the Workshop that I attended last week at Microsoft.Three days in a row, deep dive into the query optimization and performance monitoring :-) I must say, that the SQL guru Ramesh has all the tricks up in his sleeves.The workshop was very helpful and what's most important: no slide show marathon: samples after samples explained very clearly and with our own class room SQL servers we can try the same stuff while Ramesh typed his own samples.If the workshop will be rearranged, I can most willingly recommend it to anyone who wants to know what's "under the hood" of SQL Server 2008.Once again, thank you Microsoft and Ramesh to make this happen. May the force be with us all :-)Hope to see you @ the Workshop. Feel free to pass on this information to your SQL Server colleagues.-ramesh-www.sqlbits.com/speakers/r_meyyappan/default.aspx

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  • Poor System performance on my machine running Ubuntu 12.04(Beta 2 updated to the present moment)

    - by Mohammad Kamil Nadeem
    Why is it that my system dies when multitasking(it is happening from 11.10) on Ubuntu11.10(Unity), Kubuntu 11.10(KDE) and Deepin Linux which is based on 11.10(Gnome-Shell) The thing is that I thought with 12.04 I would get performance like I used to get on 11.04 on which everything used to run fine without any lag or hiccups. The same lagging(Browser starts to stutter, increased delay in the launching of dash and applications)is happening on 12.04 http://i.imgur.com/YChKB.png and http://i.imgur.com/uyXLA.png . I believe that my system configuration is sufficient for running Ubuntu as you can check here http://paste.ubuntu.com/929734/ . I had the Google voice and chat plugin installed on 12.04 so someone suggested that I should remove that and see if the performance improves but no such respite(I am having this on multiple operating system based on Ubuntu 11.10 as I have mentioned above). On a friends suggestion Ran Memory Test through Partition Magic and my system passed that fine. One thing more that I would like to know is that why when I have 2Gb Ram and 2.1GB swap does my system starts lag and run poorly when Ram consumption goes 500+. If you require anymore information I will gladly provide it.

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  • Polygons vs sprites rendering performance in Unity for windows phone 8

    - by Géry Arduino
    I'm currently building a windows phone 8 game with unity, having 111 (no more no less) sprites being updated each frames. I have a strong overhead in the profiler (70% to 90% minimum) I tried the following to get higher frame rate, I'm running it with minimum quality settings, I tried disabling and enabling V-Sync Finally I managedto get 60Fps, but I still have large overhead. I believe I should have more than 60Fps for such few amount. Moreover, I still have to implement the game logic over this so I'd like some room in my FPS to be able to work. I was wondering if it would be better in terms of performance to use polygons instead of sprites? As sprites are quite new in Unity, (that would give me around 222 triangles). Did someone tried to check the performance differences between sprites and actual mesh renderes in Unity when it comes to phones? If so what could be the best option in that case? FYI : I'm using the Windows Phone 8 emulator on Visual studio, I have a compliant computer for that so it should normally reflect the behavior of a real phone (expecting some differences but still...) EDIT : To clarify my question i wonder what is the most efficient in windows phone 8 : Sprites or Mesh renderers?

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  • Performance Overhead of Encrypted /home

    - by SabreWolfy
    I have a netbook with Windows on the second partition and Xubuntu (/ and /home) on the third partition. I selected to encrypt my home folder during installation. The performance of the netbook is adequate for the small machine that it is, but I'm looking to improve performance. I could not find much information about the overhead (CPU or drive) associated with home partition encryption. I ran the following, writing to my home partition as well as the the mounted Windows partition: dd if=/dev/zero of=~/dummy bs=512 count=10240 dd if=/dev/zero of=/media/Windows/dummy bs=512 count=10240 The first returned 2.4MB/s and the second returned 2.5MB/s. Can I therefore deduce that there is very little overhead to home folder encryption? I'm not sure if the different filesystems will make any difference (/ and /home are ext3). Update 1 I don't know why I didn't use /tmp instead of the mounted Windows folder. Only /home is encrypted, so /tmp is unencrypted ext3. The results of the dd as above are astounding: ~: 2.4 MB/s /tmp: 42.6 MB/s Comments please? The reason I am asking this is that disk access on the netbook is noticeably slow. Update 2 I timed each of the dd operations with time: ~: real 0m2.217s user 0m0.028s sys 0m2.176s /tmp: real 0m0.152s user 0m0.012s sys 0m0.136s See also: discussion on UbuntuForums.org and bug report Edit: Output of mount: /dev/sda3 on / type ext3 (rw,noatime,errors=remount-ro,user_xattr,commit=600) proc on /proc type proc (rw,noexec,nosuid,nodev) none on /sys type sysfs (rw,noexec,nosuid,nodev) fusectl on /sys/fs/fuse/connections type fusectl (rw) none on /sys/kernel/debug type debugfs (rw) none on /sys/kernel/security type securityfs (rw) none on /dev type devtmpfs (rw,mode=0755) none on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620) none on /dev/shm type tmpfs (rw,nosuid,nodev) none on /var/run type tmpfs (rw,nosuid,mode=0755) none on /var/lock type tmpfs (rw,noexec,nosuid,nodev) binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,noexec,nosuid,nodev) gvfs-fuse-daemon on /home/USER/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=USER) `

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  • How to improve batching performance

    - by user4241
    Hello, I am developing a sprite based 2D game for mobile platform(s) and I'm using OpenGL (well, actually Irrlicht) to render graphics. First I implemented sprite rendering in a simple way: every game object is rendered as a quad with its own GPU draw call, meaning that if I had 200 game objects, I made 200 draw calls per frame. Of course this was a bad choice and my game was completely CPU bound because there is a little CPU overhead assosiacted in every GPU draw call. GPU stayed idle most of the time. Now, I thought I could improve performance by collecting objects into large batches and rendering these batches with only a few draw calls. I implemented batching (so that every game object sharing the same texture is rendered in same batch) and thought that my problems are gone... only to find out that my frame rate was even lower than before. Why? Well, I have 200 (or more) game objects, and they are updated 60 times per second. Every frame I have to recalculate new position (translation and rotation) for vertices in CPU (GPU on mobile platforms does not support instancing so I can't do it there), and doing this calculation 48000 per second (200*60*4 since every sprite has 4 vertices) simply seems to be too slow. What I could do to improve performance? All game objects are moving/rotating (almost) every frame so I really have to recalculate vertex positions. Only optimization that I could think of is a look-up table for rotations so that I wouldn't have to calculate them. Would point sprites help? Any nasty hacks? Anything else? Thanks.

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  • How to check system performance?

    - by Woltan
    Hi all, I am a new Ubuntu user and really like the look and the features of the OS. However, I have a feeling that the performance could be better. With that I mean: Somehow the scrolling within firefox of sites seems laggy. I do not know how I should measure it but there is a difference. Not that it is unusable but it is aggravating. Java programs are running really slow. As a comparison (I know it is not a fair one), I tried to run a game using wine. The graphic specifications using windows were much higher (1600x1200) with a high level of detail, and in ubuntu with the lowest level of detail 1024x768 was the maximum. (My graphics card is a GeForce GTS 450 with 1gb RAM) Coming to my question: Is there a way to measure the performance of 3D acceleration, java applets, firefox scrolling etc. with a tool and compare it with lets say a windows OS or other users having almost the same hardware? Maybe it is a setup issue where some fundamental drivers are missing or something!? Any help, link, suggestion is appreciated! Cherio Woltan

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  • Demantra Performance Clustering Factor Out of Order Ratio TABLE_REORG CHECK_REORG (Doc ID 1594372.1)

    - by user702295
    Hello!   There is a new document available: Demantra Performance Clustering Factor Out of Order Ratio TABLE_REORG CHECK_REORG (Doc ID 1594372.1) Demantra Performance Clustering Factor Out of Order Ratio TABLE_REORG CHECK_REORG The table reorganization can be setup to automatically run in version 7.3.1.5.  In version 12.2.2 we run the TABLE_REORG.CHECK_REORG function at every appserver restart. If the function recommends a reorg then we strongly encourage to reorg the database object.  This is documented in the official docs. In versions 7.3.1.3 and 7.3.1.4, the TABLE_REORG module exists and can be used. It has two main functions that are documented in the Implementation Guide Supplement, Release 7.3, Part No. E26760-03, chapter 4. In short, if you are using version 7.3.1.3 or higher, you can check for the need to run a reorg by doing the following 2 steps: 1. Run TABLE_REORG.CHECK_REORG('T'); 2. Check the table LOG_TABLE_REORG for recommendations If you are on a version before 7.3.1.3, you will need to follow the instructions below to determine if you need to do a manual reorg. How to determine if a table reorg is needed 1. It is strongly encouraged by DEV that You gather statistics on the required table.  The prefered percentage for the gather is 100%. 2. Run the following SQL to evaluate how table reorg might affect Primary Key (PK) based access:   SELECT ui.index_name,trunc((ut.num_rows/ui.clustering_factor)/(ut.num_rows/ut.blocks),2) FROM user_indexes ui, user_tables ut, user_constraints uc WHERE ui.table_name=ut.table_name AND ut.table_name=uc.table_name AND ui.index_name=uc.index_name AND UC.CONSTRAINT_TYPE='P' AND ut.table_name=upper('&enter_table_name');   3. Based on the result: VALUE ABOVE 0.75 - DOES NOT REQUIRE REORG VALUE BETWEEN 0.5 AND 0.75 - REORG IS RECOMMENDED VALUE LOWER THAN 0.5 - IT IS HIGHLY RECOMMENDED TO REORG

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  • Why don't we just fix Javascript?

    - by Jan Meyer
    Javascript sucks because of a few fatalities well pointed out by Douglas Crockford. We talk a lot about it. But the point here is, why we don't fix it? Coffeescript of course does that and a lot more. But the question here is another: if we provide a webservice that can convert one version of Javascript to the next, and so on, we can keep the language up to date. Such a conversion allows old code to run, albeit with an ever-increasing startup delay, as newer browsers convert old code to the new syntax. To avoid that delay, the site only needs to take the output of the code-transform and paste it in! The effort has immediate benefits for those businesses interested in the results. The rest can sleep tight: their code will continue to run. If we provide backward code-transformation also, then elder browsers can also run ANY new code! Migration scripts should be created by those that make changes to a language. Today they don't, which is in itself a fundamental omission! It should be am obvious part of their job to provide them, as their job isn't really done without them. The onus of making it work should be on them. With this system Any site will be able to run in Any browser, but new code will run best on the newest browsers. This way we reap the benefit of an up-to-date and productive development environment, where today we suffer, supposedly because of yesterday. This is a misconception. We are all trapped in committee-thinking, and we drag along things that only worsen our performance over time! We cause an ever increasing complexity that is hard to underestimate. Javascript is easily fixed. The fact is we don't. As an example, I have seen Patrick Michaud tackle the migration problem in PmWiki. It included forward migration scripts. Whenever syntax changes were made, a migration script was added to transform pages to the new syntax. As far as I know, ALL migrations have worked flawlessly. In other words, we don't tackle the migration problem, we just drag it along. We are incompetent! And why is that? Because technically incompetent people feel they must decide for us. Because they are incompetent, fear rules them. They are obnoxiously conservative, and we suffer the consequence of bad leadership. But the competent don't need to play by the same rules. They can (and must) change them. They are the path forward. It is about time to leave the past behind, and pursue the leanest meanest, no, eternal functionality. That would in and of itself revolutionize programming. So, why don't we stop whining and fix programming? Begin with Javascript and change the world. Even if the browser doesn't hook into this system, coders could. So language updaters should take it upon them to provide migration scripts. Once they exist, browsers may take advantage of them.

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