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  • remove item from array javascript

    - by Red
    I was trying to remove some items from an array , Array.prototype.remove = function(from, to) { var rest = this.slice((to || from) + 1 || this.length); this.length = from < 0 ? this.length + from : from; return this.push.apply(this, rest); }; var BOM = [0,1,0,1,0,1,1]; var bomlength = BOM.length; for(var i = 0; i < IDLEN ;++i) { if( BOM[i] == 1) { BOM.remove(i); //IDLEN--; } } RESULT IS BOM = [0,0,0,1]; expected result is BOM = [0,0,0]; its looks like i am doing something wrong , Please help me. Thanks.

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  • How to understand if (name in {}) in javascript?

    - by tiplip
    I encounter a js function snippet, list as follows each = function(obj, fun) { if (typeof fun != "function") { return obj } if (obj) { var return_value; if (obj.length === undefined) { for (var name in obj) { if (name in {}) { // how to undertand this line, what's purpose? continue } return_value = fun.call(obj[name], obj[name], name); if (return_value == "break") { break } } } else { for (var i = 0, length = obj.length; i < length; i++) { return_value = fun.call(obj[i], obj[i], i); if (return_value == "break") { break } } } } return obj }; Thanks for your answer:)

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  • Tigther code - javascript object array

    - by Scott Silvi
    Inside the callback of a $.getJSON call, I have the code outlined below. The first for block aggregates 'total' & assigns values to sov[i]. The map function calculates the percentage of total. I then instantiate a variable called sovData. With the jQuery Flot graph, any objects that are empty aren't added to the pie chart, so this works for up to 7 different slices/datasets. What I'd like to do is only initialize the ones I need (e.g. sovData would have up to 'howMany - 1' (kws.length -1 ) objects inside of it, likely via something similar to dashboards[i] & sov[i]. How would I do this? Code: var sov = [], howMany = kws.length, total = 0, i = 0; for ( i; i < howMany; i++) { total += sov[ i ] = +parseInt(data.sov['sov' + ( i+1 ) ],10) || 0; } var dashboards = data.dashboards; sov = $.map( sov, function(v) { var s = Math.round( ( (v / total) * 10e3 ) / 100); return s < 1 ? 1 : s; }); var sovData = [{ label : dashboards[0], data : sov[0] }, { label : dashboards[1], data : sov[1] }, { label : dashboards[2], data : sov[2] }, { label : dashboards[3], data : sov[3] }, { label : dashboards[4], data : sov[4] }, { label : dashboards[5], data : sov[5] }, { label : dashboards[6], data : sov[6] } ]

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  • Howto create own Jquery Like Function in Javascript?

    - by streetparade
    How can i create a function which looks like the jquery callback $ Say i want to call a element with id= "mydiv". i want to be able to call it like var div = $("mydiv").value; i think the function should look like function $(element) { return document.getElementById(element); } Is that the right way to do it, or do you prefer another way to solve it?

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  • Async run for javascript by using listeners

    - by CharlieShi
    I have two functions, the names are Function3, Function4, Function3 will send request to server side to get jsondata by using ajax, which, however, will take about 3 seconds to complete. Function4 is a common function which will wait for Function3's result and then action. My code puts below: function ajaxRequest(container) { $.ajax({ url: "Home/GetResult", type: "post", success: function (data) { container.append(data.message); } }); } var eventable = { on: function (event, cb) { $(this).on(event, cb); }, trigger: function (event) { $(this).trigger(event); } } var Function3 = { run: function () { var self = this; setTimeout(function () { ajaxRequest($(".container1")); self.trigger('done'); }, 500); } } var Function4 = { run: function () { var self = this; setTimeout(function () { $(".container1").append("Function4 complete"); self.trigger('done'); },500); } } $.extend(Function3, eventable); $.extend(Function4, eventable); Function3.on('done', function (event) { Function4.run(); }); Function4.on('done', function () { $(".container1").append("All done"); }); Function3.run(); but now the problem is, when I start the code , it always show me the result as : first will appear "Function4 complete", then "All done" follows, 3 seconds later, "Function3 complete" will appear. That's out of my expection because my expection is "Function3 complete" comes first, "Function4 complete" comes second and "All done" is expected as the last one. Anyone can help me on this? thx in advice. EDIT: I have included all the functions above now. Also, you can check the js script in JSFIDDER: http://jsfiddle.net/sporto/FYBjc/light/ I have replaced the function in JSFIDDER from a common array push action to ajax request.

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  • make selectable area using javascript

    - by Mher
    lets say I have a html page. <html> <body> ... This is my HTML Page, full of html objects and mouse events on them ... <div id='blocker' style="height: 100%; position: absolute; width: 100%; top: 0px; left: 0px; right: 0px; bottom: 0px; z-index: 1001; background: none repeat scroll 0% 0% black; opacity: 0.5;"></div> <div id='window_to_my_html_page' style="display: block; left: 50px; top: 50px; width: 200px; height: 200px; z-index: 1002; position: absolute;"></div> </body> </html> In this example div which id is 'blocker' will block all mouse events from my page. All my HTML page elements behind of my second div(which id is 'window_to_my_html_page') must be active, all mouse events must work on them, this div must be like a window to my HTML page I want to make all elements from my HTML page active(to work as normal) inside this area (left: 50px; top: 50px; width: 200px; height: 200px).... and other content, outside of this area make inactive The question: how can I do it?

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  • javascript form reset function not working

    - by daniel
    <form name="mysqlDetails"> <label class="text">url:</label><input id="url" type="text" name="url"/><br/> <label class="text">country:</label><input id="country" type="text" name="country"/><br/> ... <input type="button" id="button" value="save" onclick="ajax.insert('mysqlDetails')"/> <input type="reset" id="clear" value="clear"/> <input type="checkbox" id="autoclear"/><label>autoclear</label> </form> function autoclear(frm){ if(document.forms[frm].getElementById('autoclear').checked==true){ document.forms[frm].reset(); document.forms[frm].getElementById('autoclear').checked=true; } } this.connect=function(frm){ if (isFirefox() && firefoxVersion() >= 3) { httpReq.onload = check; } else { httpReq.onreadystatechange = check; } httpReq.open('GET',url(frm),false); httpReq.send(null); autoclear(frm); } js is located in external file. executing form reset with an non-external file function works fine. why?

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  • [JavaScript] Function making a slight miscalculation.

    - by Stanni
    Hi, To begin with, I have a database that holds map data for a game I am creating. A script on my page uses JSON to retrieve a certain amount of that data from the database and store it in an array. When the data is retrieved it goes through a function that finds out how many individual tiles are used in that particular area. Here is the code: var xmlhttp = new XMLHttpRequest; xmlhttp.onreadystatechange = function(){ if(xmlhttp.readyState == 4){ var map = JSON.parse(xmlhttp.responseText); var mapTiles = new Array; for(var count = 0; count < map.length; count ++){ if(map[count]){ if(map[count]['tile'] in mapTiles == false){ mapTiles.push(map[count]['tile']); } } } alert(mapTiles); } } For each time the script finds a tile number that isn't already in the mapTiles array it adds it to it. Currently, the script is fetching 1024 records that all but one contain the tile value of '1' the other of which contains the tile value of '2'. This means that when I alert the mapTiles array it should display "1, 2" but instead it displays "1, 1, 2". So there is a slight error in the script but I cannot find it.

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  • Javascript trouble changing opacity

    - by Ghilliedrone
    I'm making script that fades 3 pictures out in order, but the pictures' opacity aren't changing. The if statements are reached but the pictures do not change. The first picture changes to 1 opacity on the page load, so I don't see why it wouldn't work in my function. window.onload = function() { document.getElementById("img1").style.opacity = 1; setInterval(swapPictures, 2000); }; var swapPictures = function(){ if(typeof swapPictures.img1v === 'undefined'){ swapPictures.img1v = true; } if(typeof swapPictures.img2v === 'undefined'){ swapPictures.img2v = false; } if(typeof swapPictures.img3v === 'undefined'){ swapPictures.img3v = false; } if(swapPictures.img1v && !swapPictures.img2v && !swapPictures.img3v){ swapPictures.img1v = !swapPictures.img1v; swapPictures.img2v = !swapPictures.img2v; document.getElementById("img1").style.opacity = .4; document.getElementById("imgtwo").style.opactiy = 1; }else if(!swapPictures.img1v && swapPictures.img2v && !swapPictures.img3v){ swapPictures.img2v = !swapPictures.img2v; swapPictures.img3v = !swapPictures.img3v; document.getElementById("imgtwo").style.opacity = .4; document.getElementById("imgthree").style.opactiy = 1; }else if(!swapPictures.img1v && !swapPictures.img2v && swapPictures.img3v){ swapPictures.img3v = !swapPictures.img3v; swapPictures.img1v = !swapPictures.img1v; document.getElementById("imgthree").style.opacity = .4; document.getElementById("img1").style.opactiy = 1; } };

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  • Javascript A thank you page with user name on it

    - by Sarahfromnowhere
    I have a form where a user input name and other contact information. I validate the input and then redirect to a thank you page. I wanted to personalize the page by having the user name appear as part of the thank you note. I tried document.getElementById(Name1).value to retrieve the value of the Name but it it is giving Undefined. Is there a way for me to set the value of the Name1 field to another variable that I call again to include it in my text message?

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  • Javascript handle 2 data attribute

    - by user3530661
    I need to use data attribute in my html like <div id="userlist" data-user="A.A.M"></div> then I need to alert the data-user I used var userlist = document.getElementById("userlist"); var show = userlist.getAttribute("data-user"); alert(show); My question is how to handle many data-user in the html like <div id="userlist" data-user="A.A.M"></div> <div id="userlist2" data-user="A.A.M2"></div> to alert A.A.M and A.A.M2 Thanks in advance and sorry for my bad English.

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  • Improperly called Javascript function (parameter issue)

    - by 13rave
    I am trying to echo some HTML using PHP in a div. Everything was working until I tried to pass a parameter to the onclick=\"loadpuzzle()\" function. It ran fine when I tried onclick=\"loadpuzzle(4)\" and the function took the parameter and executed normally, but what I need is to pass the value from $row['puzzlename'] as the parameter, which I assume is a string (and so I enclosed it in quotation marks). echo "<td><input id=\"".$row['puzzlename']."\" type=\"radio\" name=\"puzzle-set\" class=\"puzzle_selector\" onclick=\"loadpuzzle(\"".$row['puzzlename']."\")\"/> <label for=\"".$row['puzzlename']."\" class=\"puzz_label\">".$row['puzzlename']."</label></td>"; I am getting a weird error in Safari when I try to run this. "Unexpected token: '}' ". Does anyone know what I am doing wrong here? Why won't it take this parameter? Thank you!

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  • options[Text] is null or not an object in javascript

    - by user9167
    I am getting options[text] is null or not an object error. What i am trying to do here is i am checking what all multi select lookup column values are selected , comparing them with the value in an array and then removing them var responsibleselected = returntags("select","Responsibility selected values"); for(var i=0;i<responsibleselected.options.length;i++) { if(responsibleselected.options[i].selected == true) { for(var j=0;j< ResponsibleArray.length;j++) { if(responsibleselected.options[i].text == ResponsibleArray[j])//throws error here { GipRemoveSelectedItems(ctl00_m_g_6ad915a8_68ea_4c76_b67a_ad1215320288_ff391_ctl00_ctl00_MultiLookupPicker_m); } } } }

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  • ? and function javascript

    - by Rixius
    is there any way to map the ? key to the function keyword? so that these work: var rFalse = ?() { return false; } (?(){ var str = "i'm in a closure"; }()); window.onload = ?() { alert('window loaded'); } I know that they are attempting to put a shortened function keyword in ecmascript v6, but I'm wondering if it is possible to do it now.

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  • jQuery Globalization Plugin from Microsoft

    - by ScottGu
    Last month I blogged about how Microsoft is starting to make code contributions to jQuery, and about some of the first code contributions we were working on: jQuery Templates and Data Linking support. Today, we released a prototype of a new jQuery Globalization Plugin that enables you to add globalization support to your JavaScript applications. This plugin includes globalization information for over 350 cultures ranging from Scottish Gaelic, Frisian, Hungarian, Japanese, to Canadian English.  We will be releasing this plugin to the community as open-source. You can download our prototype for the jQuery Globalization plugin from our Github repository: http://github.com/nje/jquery-glob You can also download a set of samples that demonstrate some simple use-cases with it here. Understanding Globalization The jQuery Globalization plugin enables you to easily parse and format numbers, currencies, and dates for different cultures in JavaScript. For example, you can use the Globalization plugin to display the proper currency symbol for a culture: You also can use the Globalization plugin to format dates so that the day and month appear in the right order and the day and month names are correctly translated: Notice above how the Arabic year is displayed as 1431. This is because the year has been converted to use the Arabic calendar. Some cultural differences, such as different currency or different month names, are obvious. Other cultural differences are surprising and subtle. For example, in some cultures, the grouping of numbers is done unevenly. In the "te-IN" culture (Telugu in India), groups have 3 digits and then 2 digits. The number 1000000 (one million) is written as "10,00,000". Some cultures do not group numbers at all. All of these subtle cultural differences are handled by the jQuery Globalization plugin automatically. Getting dates right can be especially tricky. Different cultures have different calendars such as the Gregorian and UmAlQura calendars. A single culture can even have multiple calendars. For example, the Japanese culture uses both the Gregorian calendar and a Japanese calendar that has eras named after Japanese emperors. The Globalization Plugin includes methods for converting dates between all of these different calendars. Using Language Tags The jQuery Globalization plugin uses the language tags defined in the RFC 4646 and RFC 5646 standards to identity cultures (see http://tools.ietf.org/html/rfc5646). A language tag is composed out of one or more subtags separated by hyphens. For example: Language Tag Language Name (in English) en-AU English (Australia) en-BZ English (Belize) en-CA English (Canada) Id Indonesian zh-CHS Chinese (Simplified) Legacy Zu isiZulu Notice that a single language, such as English, can have several language tags. Speakers of English in Canada format numbers, currencies, and dates using different conventions than speakers of English in Australia or the United States. You can find the language tag for a particular culture by using the Language Subtag Lookup tool located here:  http://rishida.net/utils/subtags/ The jQuery Globalization plugin download includes a folder named globinfo that contains the information for each of the 350 cultures. Actually, this folder contains more than 700 files because the folder includes both minified and un-minified versions of each file. For example, the globinfo folder includes JavaScript files named jQuery.glob.en-AU.js for English Australia, jQuery.glob.id.js for Indonesia, and jQuery.glob.zh-CHS for Chinese (Simplified) Legacy. Example: Setting a Particular Culture Imagine that you have been asked to create a German website and want to format all of the dates, currencies, and numbers using German formatting conventions correctly in JavaScript on the client. The HTML for the page might look like this: Notice the span tags above. They mark the areas of the page that we want to format with the Globalization plugin. We want to format the product price, the date the product is available, and the units of the product in stock. To use the jQuery Globalization plugin, we’ll add three JavaScript files to the page: the jQuery library, the jQuery Globalization plugin, and the culture information for a particular language: In this case, I’ve statically added the jQuery.glob.de-DE.js JavaScript file that contains the culture information for German. The language tag “de-DE” is used for German as spoken in Germany. Now that I have all of the necessary scripts, I can use the Globalization plugin to format the product price, date available, and units in stock values using the following client-side JavaScript: The jQuery Globalization plugin extends the jQuery library with new methods - including new methods named preferCulture() and format(). The preferCulture() method enables you to set the default culture used by the jQuery Globalization plugin methods. Notice that the preferCulture() method accepts a language tag. The method will find the closest culture that matches the language tag. The $.format() method is used to actually format the currencies, dates, and numbers. The second parameter passed to the $.format() method is a format specifier. For example, passing “c” causes the value to be formatted as a currency. The ReadMe file at github details the meaning of all of the various format specifiers: http://github.com/nje/jquery-glob When we open the page in a browser, everything is formatted correctly according to German language conventions. A euro symbol is used for the currency symbol. The date is formatted using German day and month names. Finally, a period instead of a comma is used a number separator: You can see a running example of the above approach with the 3_GermanSite.htm file in this samples download. Example: Enabling a User to Dynamically Select a Culture In the previous example we explicitly said that we wanted to globalize in German (by referencing the jQuery.glob.de-DE.js file). Let’s now look at the first of a few examples that demonstrate how to dynamically set the globalization culture to use. Imagine that you want to display a dropdown list of all of the 350 cultures in a page. When someone selects a culture from the dropdown list, you want all of the dates in the page to be formatted using the selected culture. Here’s the HTML for the page: Notice that all of the dates are contained in a <span> tag with a data-date attribute (data-* attributes are a new feature of HTML 5 that conveniently also still work with older browsers). We’ll format the date represented by the data-date attribute when a user selects a culture from the dropdown list. In order to display dates for any possible culture, we’ll include the jQuery.glob.all.js file like this: The jQuery Globalization plugin includes a JavaScript file named jQuery.glob.all.js. This file contains globalization information for all of the more than 350 cultures supported by the Globalization plugin.  At 367KB minified, this file is not small. Because of the size of this file, unless you really need to use all of these cultures at the same time, we recommend that you add the individual JavaScript files for particular cultures that you intend to support instead of the combined jQuery.glob.all.js to a page. In the next sample I’ll show how to dynamically load just the language files you need. Next, we’ll populate the dropdown list with all of the available cultures. We can use the $.cultures property to get all of the loaded cultures: Finally, we’ll write jQuery code that grabs every span element with a data-date attribute and format the date: The jQuery Globalization plugin’s parseDate() method is used to convert a string representation of a date into a JavaScript date. The plugin’s format() method is used to format the date. The “D” format specifier causes the date to be formatted using the long date format. And now the content will be globalized correctly regardless of which of the 350 languages a user visiting the page selects.  You can see a running example of the above approach with the 4_SelectCulture.htm file in this samples download. Example: Loading Globalization Files Dynamically As mentioned in the previous section, you should avoid adding the jQuery.glob.all.js file to a page whenever possible because the file is so large. A better alternative is to load the globalization information that you need dynamically. For example, imagine that you have created a dropdown list that displays a list of languages: The following jQuery code executes whenever a user selects a new language from the dropdown list. The code checks whether the globalization file associated with the selected language has already been loaded. If the globalization file has not been loaded then the globalization file is loaded dynamically by taking advantage of the jQuery $.getScript() method. The globalizePage() method is called after the requested globalization file has been loaded, and contains the client-side code to perform the globalization. The advantage of this approach is that it enables you to avoid loading the entire jQuery.glob.all.js file. Instead you only need to load the files that you need and you don’t need to load the files more than once. The 5_Dynamic.htm file in this samples download demonstrates how to implement this approach. Example: Setting the User Preferred Language Automatically Many websites detect a user’s preferred language from their browser settings and automatically use it when globalizing content. A user can set a preferred language for their browser. Then, whenever the user requests a page, this language preference is included in the request in the Accept-Language header. When using Microsoft Internet Explorer, you can set your preferred language by following these steps: Select the menu option Tools, Internet Options. Select the General tab. Click the Languages button in the Appearance section. Click the Add button to add a new language to the list of languages. Move your preferred language to the top of the list. Notice that you can list multiple languages in the Language Preference dialog. All of these languages are sent in the order that you listed them in the Accept-Language header: Accept-Language: fr-FR,id-ID;q=0.7,en-US;q=0.3 Strangely, you cannot retrieve the value of the Accept-Language header from client JavaScript. Microsoft Internet Explorer and Mozilla Firefox support a bevy of language related properties exposed by the window.navigator object, such as windows.navigator.browserLanguage and window.navigator.language, but these properties represent either the language set for the operating system or the language edition of the browser. These properties don’t enable you to retrieve the language that the user set as his or her preferred language. The only reliable way to get a user’s preferred language (the value of the Accept-Language header) is to write server code. For example, the following ASP.NET page takes advantage of the server Request.UserLanguages property to assign the user’s preferred language to a client JavaScript variable named acceptLanguage (which then allows you to access the value using client-side JavaScript): In order for this code to work, the culture information associated with the value of acceptLanguage must be included in the page. For example, if someone’s preferred culture is fr-FR (French in France) then you need to include either the jQuery.glob.fr-FR.js or the jQuery.glob.all.js JavaScript file in the page or the culture information won’t be available.  The “6_AcceptLanguages.aspx” sample in this samples download demonstrates how to implement this approach. If the culture information for the user’s preferred language is not included in the page then the $.preferCulture() method will fall back to using the neutral culture (for example, using jQuery.glob.fr.js instead of jQuery.glob.fr-FR.js). If the neutral culture information is not available then the $.preferCulture() method falls back to the default culture (English). Example: Using the Globalization Plugin with the jQuery UI DatePicker One of the goals of the Globalization plugin is to make it easier to build jQuery widgets that can be used with different cultures. We wanted to make sure that the jQuery Globalization plugin could work with existing jQuery UI plugins such as the DatePicker plugin. To that end, we created a patched version of the DatePicker plugin that can take advantage of the Globalization plugin when rendering a calendar. For example, the following figure illustrates what happens when you add the jQuery Globalization and the patched jQuery UI DatePicker plugin to a page and select Indonesian as the preferred culture: Notice that the headers for the days of the week are displayed using Indonesian day name abbreviations. Furthermore, the month names are displayed in Indonesian. You can download the patched version of the jQuery UI DatePicker from our github website. Or you can use the version included in this samples download and used by the 7_DatePicker.htm sample file. Summary I’m excited about our continuing participation in the jQuery community. This Globalization plugin is the third jQuery plugin that we’ve released. We’ve really appreciated all of the great feedback and design suggestions on the jQuery templating and data-linking prototypes that we released earlier this year.  We also want to thank the jQuery and jQuery UI teams for working with us to create these plugins. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. You can follow me at: twitter.com/scottgu

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  • How can a Virtual PC with Win XP install the East Asian Language? (or does any browser come with Chi

    - by Jian Lin
    How can a Virtual PC with Win XP on it install the East Asian Language? (or does any browser come with Chinese fonts?) After setting up a virtual PC with Win XP, if Chinese font is needed, then the usual way is to go to the Control Panel, select "Regional and Language" and go to the second tab and check the box "Install Files for East Asian Languages". After clicking OK, it asks for the file cplexe.exe on the XP SP3 CD 3... and is said to be about 230MB... In such case, how can the language pack or fonts be installed? (Update: I found that it is true for Window 7's Virtual PC with XP on it, as well as the XP SP3 with IE 8 that can be downloaded in the link below.) (I downloaded the virtual hard drive file .vhd from http://www.microsoft.com/downloads/details.aspx?FamilyId=21EABB90-958F-4B64-B5F1-73D0A413C8EF&displaylang=en so there is no "CD 3"... there) Or does any browser come with all the unicode fonts without needing the OS to support it?

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  • Goto for the Java Programming Language

    - by darcy
    Work on JDK 8 is well-underway, but we thought this late-breaking JEP for another language change for the platform couldn't wait another day before being published. Title: Goto for the Java Programming Language Author: Joseph D. Darcy Organization: Oracle. Created: 2012/04/01 Type: Feature State: Funded Exposure: Open Component: core/lang Scope: SE JSR: 901 MR Discussion: compiler dash dev at openjdk dot java dot net Start: 2012/Q2 Effort: XS Duration: S Template: 1.0 Reviewed-by: Duke Endorsed-by: Edsger Dijkstra Funded-by: Blue Sun Corporation Summary Provide the benefits of the time-testing goto control structure to Java programs. The Java language has a history of adding new control structures over time, the assert statement in 1.4, the enhanced for-loop in 1.5,and try-with-resources in 7. Having support for goto is long-overdue and simple to implement since the JVM already has goto instructions. Success Metrics The goto statement will allow inefficient and verbose recursive algorithms and explicit loops to be replaced with more compact code. The effort will be a success if at least twenty five percent of the JDK's explicit loops are replaced with goto's. Coordination with IDE vendors is expected to help facilitate this goal. Motivation The goto construct offers numerous benefits to the Java platform, from increased expressiveness, to more compact code, to providing new programming paradigms to appeal to a broader demographic. In JDK 8, there is a renewed focus on using the Java platform on embedded devices with more modest resources than desktop or server environments. In such contexts, static and dynamic memory footprint is a concern. One significant component of footprint is the code attribute of class files and certain classes of important algorithms can be expressed more compactly using goto than using other constructs, saving footprint. For example, to implement state machines recursively, some parties have asked for the JVM to support tail calls, that is, to perform a complex transformation with security implications to turn a method call into a goto. Such complicated machinery should not be assumed for an embedded context. A better solution is just to expose to the programmer the desired functionality, goto. The web has familiarized users with a model of traversing links among different HTML pages in a free-form fashion with some state being maintained on the side, such as login credentials, to effect behavior. This is exactly the programming model of goto and code. While in the past this has been derided as leading to "spaghetti code," spaghetti is a tasty and nutritious meal for programmers, unlike quiche. The invokedynamic instruction added by JSR 292 exposes the JVM's linkage operation to programmers. This is a low-level operation that can be leveraged by sophisticated programmers. Likewise, goto is a also a low-level operation that should not be hidden from programmers who can use more efficient idioms. Some may object that goto was consciously excluded from the original design of Java as one of the removed feature from C and C++. However, the designers of the Java programming languages have revisited these removals before. The enum construct was also left out only to be added in JDK 5 and multiple inheritance was left out, only to be added back by the virtual extension method methods of Project Lambda. As a living language, the needs of the growing Java community today should be used to judge what features are needed in the platform tomorrow; the language should not be forever bound by the decisions of the past. Description From its initial version, the JVM has had two instructions for unconditional transfer of control within a method, goto (0xa7) and goto_w (0xc8). The goto_w instruction is used for larger jumps. All versions of the Java language have supported labeled statements; however, only the break and continue statements were able to specify a particular label as a target with the onerous restriction that the label must be lexically enclosing. The grammar addition for the goto statement is: GotoStatement: goto Identifier ; The new goto statement similar to break except that the target label can be anywhere inside the method and the identifier is mandatory. The compiler simply translates the goto statement into one of the JVM goto instructions targeting the right offset in the method. Therefore, adding the goto statement to the platform is only a small effort since existing compiler and JVM functionality is reused. Other language changes to support goto include obvious updates to definite assignment analysis, reachability analysis, and exception analysis. Possible future extensions include a computed goto as found in gcc, which would replace the identifier in the goto statement with an expression having the type of a label. Testing Since goto will be implemented using largely existing facilities, only light levels of testing are needed. Impact Compatibility: Since goto is already a keyword, there are no source compatibility implications. Performance/scalability: Performance will improve with more compact code. JVMs already need to handle irreducible flow graphs since goto is a VM instruction.

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  • Single click handler for all buttons in Javascript? Is it a pattern? Whats the benefit?

    - by Hasan Khan
    I have been told that when there are multiple buttons on the page for same purpose but targeting different item e.g. delete item on a grid of items, they say it is recommended to just register for click handler only on the top most element like 'body' and check what was clicked instead of hooking up click with every delete button. Whats the benefit of this? Creating more handlers causes problems? Is it an optimization of some sort? Is it a pattern? Does it have anything to do with performance? Where can I read more about it?

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  • New JavaScript Editor

    - by Petr
    I did not write a blog post here for a few weeks. I think the last my post was  about releasing NetBeans 7.1 in the beginning of January. The reason is not that I would change the job:), but that I have concentrated on new JavaScript support/editor. The new JavaScript editor is written basically from scratch. The answer for the question "Why from beginning again, why do you just improve the old one?" is not easy and the decision has more aspects. One of the main reasons is that the old support was written 4 years ago and the architecture is limited. Also during the time, the APIs were changed and it was very hard to keep the editor up to date. Also there is a license issue etc. In short, it is time to rewrite the old JS editor.  We build up strong community about the PHP support in NetBeans and because many PHP developers also write JavaScript code I would like to ask you for a help. There is a continual PHP build with the new JavaScript support. You can download the result of the builds here. It's a zip file. You can unzip the file anywhere, where you want. I recommend to run the build with the new userdir, to avoid damaging your current userdir. It shouldn't happened, but just to be sure:). You can achieve this through the switch --userdir. So start the unzipped file from command line from the folder, where you unzipped it, can be done with this command on unix: bin/netbeans.sh --userdir /path/to/new/userdir and on windows: bin\netbeans.exe --userdir D:\path\to\new\userdir For the developers who use continual php build already, it's well known. There is also full IDE build with the new JavaScript support for people, who need more than only PHP support.  Because the builds with the new JavaScript editor is created from a branch, there are not nightly builds available. They will be, when we merge the branch to the trunk, but so far we have to work only with the mentioned continual build. We will merge our branch after branching NetBeans 7.2 from trunk. This is also answer for the question, what release of NetBeans will contain the new JS support. It should be the release after NetBeans 7.2. I'm asking you whether you could play with the builds or better, could work in the builds with new JavaScript support and tell us every issue that you run in. It can be everything what doesn't fit you, something doesn't work as you expected, something is slow, you want change the behaviour of a feature etc. Your input / comments are very important for us and it will help us to achieve the new JavaScript support that you need.  The best way how to communicate issues is through our Bugzilla, because it is simple to track them. Sure you can write comment here:), but still I prefer Bugzilla for any issue. You can click here (you should be already log in Bugzilla), a form for the new JavaScript issue is opened, with pre-filled component Editor and NO72 keyword. I will write about the single features later, but now I will mentioned a few features that should work in better way than in the old support.  Syntactic and semantic colouring Navigator Mark Occurrences and GoTo Declaration  Code Completion Code Completion is invoked through keyboard shortcut CTRL+SPACE. The first invocation offers items that are found through a source model. Almost all editor features are based on the model, that is build from source code. There is a lot of work on the model yet, but it should offer better results. When the pop up window with code completion items is open and you press CTRL+SPACE again, then the code completion offers all elements that are in the project. In the pictures all elements that starts with letter 't'. Formatter with many options and more :) A few features are not still implemented that are supported in the old JavaScript support (for example jQuery support), but we are adding this features ASAP.

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  • Why is there no service-oriented language?

    - by Wolfgang
    Edit: To avoid further confusion: I am not talking about web services and such. I am talking about structuring applications internally, it's not about how computers communicate. It's about programming languages, compilers and how the imperative programming paradigm is extended. Original: In the imperative programming field, we saw two paradigms in the past 20 years (or more): object-oriented (OO), and service-oriented (SO) aka. component-based (CB). Both paradigms extend the imperative programming paradigm by introducing their own notion of modules. OO calls them objects (and classes) and lets them encapsulates both data (fields) and procedures (methods) together. SO, in contrast, separates data (records, beans, ...) from code (components, services). However, only OO has programming languages which natively support its paradigm: Smalltalk, C++, Java and all other JVM-compatibles, C# and all other .NET-compatibles, Python etc. SO has no such native language. It only comes into existence on top of procedural languages or OO languages: COM/DCOM (binary, C, C++), CORBA, EJB, Spring, Guice (all Java), ... These SO frameworks clearly suffer from the missing native language support of their concepts. They start using OO classes to represent services and records. This leads to designs where there is a clear distinction between classes that have methods only (services) and those that have fields only (records). Inheritance between services or records is then simulated by inheritance of classes. Technically, its not kept so strictly but in general programmers are adviced to make classes to play only one of the two roles. They use additional, external languages to represent the missing parts: IDL's, XML configurations, Annotations in Java code, or even embedded DSL like in Guice. This is especially needed, but not limited to, since the composition of services is not part of the service code itself. In OO, objects create other objects so there is no need for such facilities but for SO there is because services don't instantiate or configure other services. They establish an inner-platform effect on top of OO (early EJB, CORBA) where the programmer has to write all the code that is needed to "drive" SO. Classes represent only a part of the nature of a service and lots of classes have to be written to form a service together. All that boiler plate is necessary because there is no SO compiler which would do it for the programmer. This is just like some people did it in C for OO when there was no C++. You just pass the record which holds the data of the object as a first parameter to the procedure which is the method. In a OO language this parameter is implicit and the compiler produces all the code that we need for virtual functions etc. For SO, this is clearly missing. Especially the newer frameworks extensively use AOP or introspection to add the missing parts to a OO language. This doesn't bring the necessary language expressiveness but avoids the boiler platform code described in the previous point. Some frameworks use code generation to produce the boiler plate code. Configuration files in XML or annotations in OO code is the source of information for this. Not all of the phenomena that I mentioned above can be attributed to SO but I hope it clearly shows that there is a need for a SO language. Since this paradigm is so popular: why isn't there one? Or maybe there are some academic ones but at least the industry doesn't use one.

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  • Is there a way to catch assignments to or reads from an undefined property in JavaScript?

    - by avri
    JavaScript implements the noSuchMethod callback function for JavaScript Objects. This function is called whenever JavaScript tries to execute an undefined method of an Object. I would like to set a callback function to an Object that will be called whenever an undefined property in the Object is accessed or assigned to. I haven't found a noSuchProperty function implemented for JavaScript Objects and I am curios if there is any workaround that will achieve the same result.

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