Search Results

Search found 32581 results on 1304 pages for 'javascript common difficulties and misconceptions'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 15/1304 | < Previous Page | 11 12 13 14 15 16 17 18 19 20 21 22  | Next Page >

  • Will Google treat this JavaScript code as a bad practice?

    - by Mathew Foscarini
    I have a website that provides a custom UX experience implemented via JavaScript. When JavaScript is disabled in the browser the website falls back to CSS for the layout. To make this possible I've added a noJS class to the <body> and quickly remove it via JavaScript. <body class="noJS layout-wide"> <script type="text/javascript">var b=document.getElementById("body");b.className=b.className.replace("noJS","");</script> This caused a problem when the page loads and JavaScript is enabled. The body immediately has it's noJS class removed, and this causes the layout to appear messed up until the JavaScript code for layout is executed (at bottom of the page). To solve this I hide each article via JavaScript by adding a CSS class fix which is display:none as each article is loaded. <article id="q-3217">....</article> <script type="text/javascript">var b=document.getElementById("q-3217");b.className=b.className+" fix";</script> After the page is ready I show all the articles in the correct layout. I've read many times in Google's documentation not to hide content. So I'm worried that the Google will penalize my website for doing this.

    Read the article

  • javascript fixed timestep gameloop with requestanimation frame

    - by coffeecup
    hello i just started to read through several articles, including http://gafferongames.com/game-physics/fix-your-timestep/ ...://gamedev.stackexchange.com/questions/1589/fixed-time-step-vs-variable-time-step/ ...//dewitters.koonsolo.com/gameloop.html ...://nokarma.org/2011/02/02/javascript-game-development-the-game-loop/index.html my understanding of this is that i need the currentTime and the timeStep size and integrate all states to the next state the time which is left is then passed into the render function to do interpolation i tried to implement glenn fiedlers "the final touch", whats troubling me is that each FrameTime is about 15 (ms) and the update loop runs at about 1500 fps which seems a little bit off? heres my code this.t = 0 this.dt = 0.01 this.currTime = new Date().getTime() this.accumulator = 0.0 this.animate() animate: function(){ var newTime = new Date().getTime() , frameTime = newTime - this.currTime , alpha if ( frameTime > 0.25 ) frameTime = 0.25 this.currTime = newTime this.accumulator += frameTime while (this.accumulator >= this.dt ) { this.prev_state = this.curr_state this.update(this.t,this.dt) this.t += this.dt this.accumulator -= this.dt } alpha = this.accumulator / this.dt this.render( this.t, this.dt, alpha) requestAnimationFrame( this.animate ) } also i would like to know, are there differences between glenn fiedlers implementation and the last solution presented here ? gameloop1 gameloop2 [ sorry couldnt post more than 2 links.. ] edit : i looked into it again and adjusted the values this.currTime = new Date().getTime() this.accumulator = 0 this.p_t = 0 this.p_step = 1000/100 this.animate() animate: function(){ var newTime = new Date().getTime() , frameTime = newTime - this.currTime , alpha if(frameTime > 25) frameTime = 25 this.currTime = newTime this.accumulator += frameTime while(this.accumulator >= this.p_step){ // prevstate = currState this.update() this.p_t+=this.p_step this.accumulator -= this.p_step } alpha = this.accumulator / this.p_step this.render(alpha) requestAnimationFrame( this.animate ) now i can set the physics update rate, render runs at 60 fps and physics update at 100 fps, maybe someone could confirm this because its the first time i'm playing around with game development :-)

    Read the article

  • Designing javascript chart library

    - by coolscitist
    I started coding a chart library on top of d3js: My chart library. I read Javascript API reusability and Towards reusable charts. However, I am NOT really following the suggestions because I am not really convinced about them. This is how my library can be used to create a bubble chart: var chart = new XYBubbleChart(); chart.data = [{"xValue":200,"yValue":300},{"xValue":400,"yValue":200},{"xValue":100,"yValue":310}]; //set data chart.dataKey.x = "xValue"; chart.dataKey.y = "yValue"; chart.elementId = "#chart"; chart.createChart(); Here are my questions: It does not use chaining. Is it a big issue? Every property and function is exposed publicly. (Example: width, height are exposed in Chart.js). OOP is all about abstraction and hiding, but I don't really see the point right now. I think exposing everything gives flexibility to change property and functionality inside subclasses and objects without writing a lot of code. What could be pitfalls of such exposure? I have implemented functions like: zooming, "showing info boxes when data point is clicked" as "abilities". (example: XYZoomingAbility.js). Basically, such "abilities" accept "chart" object, play around with public variables of "chart" to add functionality. What this allows me to do is to add an ability by writing: activateZoomAbility(chartObject); My goal is to separate "visualization" from "interactivity". I want "interactivity" like: zooming to be plugged into the chart rather than built inside the chart. Like, I don't want my bubble chart to know anything about "zooming". However, I do want zoomable bubble chart. What is the best way to do this? How to test and what to test? I have written mixed tests: jasmine and actual html files so that I can test manually on browser.

    Read the article

  • Semi Fixed-timestep ported to javascript

    - by abernier
    In Gaffer's "Fix Your Timestep!" article, the author explains how to free your physics' loop from the paint one. Here is the final code, written in C: double t = 0.0; const double dt = 0.01; double currentTime = hires_time_in_seconds(); double accumulator = 0.0; State previous; State current; while ( !quit ) { double newTime = time(); double frameTime = newTime - currentTime; if ( frameTime > 0.25 ) frameTime = 0.25; // note: max frame time to avoid spiral of death currentTime = newTime; accumulator += frameTime; while ( accumulator >= dt ) { previousState = currentState; integrate( currentState, t, dt ); t += dt; accumulator -= dt; } const double alpha = accumulator / dt; State state = currentState*alpha + previousState * ( 1.0 - alpha ); render( state ); } I'm trying to implement this in JavaScript but I'm quite confused about the second while loop... Here is what I have for now (simplified): ... (function animLoop(){ ... while (accumulator >= dt) { // While? In a requestAnimation loop? Maybe if? ... } ... // render requestAnimationFrame(animLoop); // stand for the 1st while loop [OK] }()) As you can see, I'm not sure about the while loop inside the requestAnimation one... I thought replacing it with a if but I'm not sure it will be equivalent... Maybe some can help me.

    Read the article

  • Lightweight, dynamic, fully JavaScript web UI library recommendations

    - by Matt Greer
    I am looking for recommendations for a lightweight, dynamic, fully JavaScript UI library for websites. Doesn't have to be amazing visually, the end result is for simple demos I create. What I want can be summed up as "Ext-like, but not GPL'ed, and a much smaller footprint". I want to be able to construct UIs dynamically and fully through code. My need for this is currently driven by this particle designer. Depending on what query parameters you give it, the UI components change, example 1, example2. Currently this is written in Ext, but Ext's license and footprint are turn offs for me. I like UKI a lot, but it's not very good for dynamically building UIs since everything is absolutely positioned. Extending Uki to support that is something I am considering. Ideally the library would let me make UIs with a pattern along the lines of: var container = new SomeUI.Container(); container.add(new SomeUI.Label('Color Components')); container.add(new SomeUI.NumberField('R')); container.add(new SomeUI.NumberField('G')); container.add(new SomeUI.NumberField('B')); container.add(new SomeUI.CheckBox('Enable Alpha')); container.renderTo(someDiv);

    Read the article

  • Isometric Movement in Javascript In the DOM

    - by deep
    I am creating a game using Javascript. I am not using the HTML5 Canvas Element. The game requires both side view controlles, and Isometric controls, hence the movementMode variable. I have got the specific angles, but I am stuck on an aspect of this. https://chillibyte.makes.org/thimble/movement function draw() { if (keyPressed) { if (whichKey == keys.left) { move(-1,0) } if (whichKey == keys.right) { move(1,0) } if (whichKey == keys.up) { move(0,-1) } if (whichKey == keys.down) { move(0,1) } } } This gives normal up, down , left, and right. i want to refactor this so that i can plugin two variables into the move() function, which will give the movement wanted. Now for the trig. /| / | / | y / | /a___| x Take This Right angled Triangle. given that x is 1, y must be equal to tan(a) That Seems right. However, when I do Math.tan(45), i get a number similar to 1.601. Why? To Sum up this question. I have a function, and i need a function which will converts an angle to a value, which will tell me the number of pixels that i need to go up by, if i only go across 1. Is it Math.tan that i want? or is it something else?

    Read the article

  • Duplication of code (backend and javascript - knockout)

    - by Michal B.
    We have a new developer in our team. He seems a smart guy (he just came in so I cannot really judge). He started with implementing some small enhancements in the project (MVC3 web application using javascript - jquery and knockout). Let's say we have two values: A - quite complex calculation C - constant B = A + C On the screen there is value B and user can change it (normal texbox). When B changes, A changes as well because C is constant. So there is linear dependency between A and B. Now, all the calculations are done in the backend, but we need to recalculate A as user changes B (in js, I would use knockout). I thought about storing old A and B and when B changes by 10 then we know that new A will be old A + 10. He says this is dirty, because it's duplication of code (we make use of the fact that they are dependent and according to him that should be only in one place in our app). I understand it's not ideal, but making AJAX request after every key press seems a bit too much. It's a really small thing and I would not post if we haven't had long discussion about it. How do you deal with such problems? Also I can imagine that using knockout implies lots of calculations on the client side, which very often leads to duplication of the same calculations from the backend. Does anyone have links to some articles/thoughts on this topic?

    Read the article

  • New "delay" keyword for JavaScript

    - by Van Coding
    I had a great idea for a new javascript keyword "delay", but I don't know what I can do to bring it to the new specification. Also I want to know what you guys think about it and if it's even realistic. What does the delay keyword ? The delay keyword does nothing more than stop the execution of the current stack and immediately continues to the next "job" in the queue. But that's not all! Instead of discarding the stack, it adds it to the end of the queue. After all "jobs" before it are done, the stack continues to execute. What is it good for? delay could help make blocking code non-blocking while it still looks like synchronous code. A short example: setTimeout(function(){ console.log("two"); },0); console.log("one"); delay; //since there is currently another task in the queue, do this task first before continuing console.log("three"); //Outputs: one, two, three This simple keyword would allow us to create a synchronous-looking code wich is asynchronous behind the scenes. Using node.js modules, for example, would no longer be impossible to use in the browser without trickery. There would be so many possibilites with such a keyword! Is this pattern useful? What can I do to bring this into the new ECMAscript specification? Note: I asked this previously on Stack Overflow, where it was closed.

    Read the article

  • Javascript Canvas Drawing Efficiency

    - by jujumbura
    I have just recently started some experiments with game development in Javascript/HTML5, and so far it has been going pretty well. I have a simple test scene running with some basic input handling, and a hundred-ish drawImage() calls with a few transforms. This all runs great on Chrome, but unfortunately, it already chugs on Firefox. I am using a very large canvas ( 1920 x 1080 ), but it doesn't seem like I should be hitting my limit already. So on that note, I was hoping to ask a few questions: 1) What exactly is done on the CPU vs. the GPU in terms of canvas and drawImage()? I'm afraid the answer is probably "it depends on the browser", but can anybody give me some rules of thumb? I naively imagined that each drawImage call results in a textured quad on the GPU with the canvas effectively being a render target, but I'm wondering if I'm pretty far off base there... 2) I have seen posts here and there with people saying not to use the translate(), rotate(), scale() functions when drawing on the canvas. Am I adding a lot of overhead just by adding a translate() call, as opposed to passing in the x,y to drawImage()? Some people suggest using "transate3d", etc., which are CSS properties, but I'm not sure how to use them within a scene. Can they be used for animated sprites within a single canvas? 3) I have also seen a lot of posts with people mentioning that pre-building canvases and then re-using them is a lot faster than issuing all the individual draw calls again. I am guessing that my background should definitely be pre-built into a canvas, but how far should I take this? Should I maintain an individual canvas for each sprite, to cache all static image data when not animating? Thank you much for your advice!

    Read the article

  • Javascript MVC in principle

    - by Michael
    Suppose I want to implement MVC in JavaScript. I am not asking about MVC frameworks. I am asking how to build it in principle. Let's consider a search page of an e-commerce site, which works s follows: User chooses a product and its attributes and press a "search" button. Application sends the search request to the server, receives a list of products. Application displays the list in the web page. I think the Model holds a Query and list of Product objects and "publishes" such events as "query updated", "list of products updated", etc. The Model is not aware of DOM and server, or course. View holds the entire DOM tree and "subscribes" to the Model events to update the DOM. Besides, it "publishes" such events as "user chose a product", "user pressed the search button" etc. Controller does not hold any data. It "subscribes" to the View events, calls the server and updates the Model. Does it make sense?

    Read the article

  • Unable to debug an encodded javascript?

    - by miles away
    I’m having some problems debugging an encoded javacscript. This script I’m referring to given in this link over here. The encoding here is simple and it works by shifting the unicodes values to whatever Codekey was use during encoding. The code that does the decoding is given here in plain English below:- <script language="javascript"> function dF(s){ var s1=unescape(s.substr(0,s.length-1)); var t=''; for(i=0;i<s1.length;i++)t+=String.fromCharCode(s1.charCodeAt(i)-s.substr(s.length-1,1)); document.write(unescape(t)); } </script> I’m interested in knowing or understanding the values (e.g s1,t). Like for example when the value of i=0 what values would the following attributes / method would hold s1.charCodeAt(i) and s.substr(s.length-1,1) The reason I’m doing this is to understand as to how a CodeKey function really works. I don’t see anything in the code above which tells it to decode on the basis of codekey value. The only thing I can point in the encoding text is the last character which is set to 1 , 2 ,3 or 4 depending upon the codekey selected during encoding process. One can verify using the link I have given above. However, to debug, I’m using firebug addon with the script running as localhost on my wamp server. I’m able to put a breakpoint on the js using firebug but I’m unable to retrieve any of the user defined parameters or functions I mentioned above. I want to know under this context what would be best way to debug this encoded js.

    Read the article

  • What should I "forget" when going to Javascript?

    - by ElGringoGrande
    I went from C=64 Basic and assembler to FORTRAN and C to C++ and Java. Professionally I started in Visual Basic for applications then to Visual Basic 4, 5, 6. After that VB.NET AND C# with some Java here and there. I have played with Ruby and Python and found both fun. During each step I never felt like I had to forget what I had learned before. I always felt like I was just learning better and/or slightly different ways of doing things but the difference was not major. The difference was like the difference between American, Australian and British English. (Maybe assembler was Latin and FORTRAN was Spanish.) But now I am using JavaScript to do real, actual work. (Before used it as a "Scripting" language pure a simple.) And I just feel like I have to forget some things to become proficient in it. It feels like some old Egyptian language. What should I forget? Is it just that code organization is different (no real classes so no one class one file)? Or is it something more basic?

    Read the article

  • JavaScript and callback nesting

    - by Jake King
    A lot of JavaScript libraries (notably jQuery) use chaining, which allows the reduction of this: var foo = $(".foo"); foo.stop(); foo.show(); foo.animate({ top: 0 }); to this: $(".foo").stop().show().animate({ top: 0 }); With proper formatting, I think this is quite a nice syntactic capability. However, I often see a pattern which I don't particularly like, but appears to be a necessary evil in non-blocking models. This is the ever-present nesting of callback functions: $(".foo").animate({ top: 0, }, { callback: function () { $.ajax({ url: 'ajax.php', }, { callback: function () { ... } }); } }); And it never ends. Even though I love the ease non-blocking models provide, I hate the odd nesting of function literals it forces upon the programmer. I'm interesting in writing a small JS library as an exercise, and I'd love to find a better way to do this, but I don't know how it could be done without feeling hacky. Are there any projects out there that have resolved this problem before? And if not, what are the alternatives to this ugly, meaningless code structure?

    Read the article

  • Help w/ iPad 1 performance for tile-based DOM Javascript game

    - by butr0s
    I've made a 2D tile-based game with DOM/Javascript. For each level, the map data is loaded and parsed, then lots of tiles ( elements) are drawn onto a larger "map" element. The map is inside of a container that hides overflow, so I can move the map element around by positioning it absolutely. Works a treat on desktop browsers, and my iPad 2. My problem is that performance is really bad on iPad 1. The performance hit is directly related to all the tile elements in my map, because when I remove or reduce the number of tiles drawn, performance improves. Optimizing my collision detection loop has no effect. My first thought was to batch groups of tiles into containers, then hide/show them based on proximity to the player, however this still causes a huge hiccup when the player moves and a new group of tiles is displayed (offscreen). Actually removing the out-of-sight elements from the DOM, then re-adding them as necessary is no faster. Anyone know of any tips that might speed up DOM performance here? My map is 1920 x 1920 pixels, so as far as I know should be within the WebKit texture limit on iOS 5/iPad. The map is being moved with CSS3 transforms, and I've picked all the other obvious low-hanging fruit.

    Read the article

  • Javascript storing data

    - by user985482
    Hi I am a beginner web developer and am trying to build the interface of a simple e-commerce site as a personal project.The site has multiple pages with checkboxes.When someone checks an element it retrives the price of the element and stores it in a variable.But when I go to the next page and click on new checkboxes products the variable automaticly resets to its original state.How can I save the value of that variable in Javascript? This is the code I've writen using sessionStorage but it still dosen't work when I move to next page the value is reseted. How can I wright this code so that i dosen't reset on each page change.All pages on my website use the same script. $(document).ready(function(){ var total = 0; $('input.check').click(function(){ if($(this).attr('checked')){ var check = parseInt($(this).parent().children('span').text().substr(1 , 3)); total+=check; sessionStorage.var_name=0 + total; alert(sessionStorage.var_name); }else{ var uncheck = parseInt($(this).parent().children('span').text().substr(1 , 3)); total-=uncheck; } })

    Read the article

  • Javascript Event in Innerhtml Resulting from PHP Server Script

    - by user144527
    I'm (very slowly) making a website, and I'm creating a search engine for the database, which is essential to organize the dependencies during data entry. Anyway, what I would like is to type a few keywords into a box, have a menu pop up with various search results, and have the box fill with the ID number of the selected entry when it's clicked. Currently, I have a document called search.php which fills a div called search-output using xmlhttp.open() and the innerhtml property. Everything is working perfectly except for filling the original search box with the ID number when clicking. My first attempt was to add an onclick event to each entry in the output from search.php. Unfortunately, I found that javascript inserted into innerhtml is not run for security reasons. I've been Googling for hours but haven't been able to find a solution. How can I get the original search text box to fill with the correct ID when I click it? Is what I'm doing a good setup for the results I desire, or is there a better way to integrate search features into data entry?

    Read the article

  • Choosing a JavaScript Asynch-Loader

    - by Prisoner ZERO
    I’ve been looking at various asynchronous resource-loaders and I’m not sure which one to use yet. Where I work we have disparate group-efforts whose class-modules may use different versions of jQuery (etc). As such, nested dependencies may differ, as well. I have no control over this, so this means I need to dynamically load resources which may use alternate versions of the same library. As such, here are my requirements: Load JavaScript and CSS resource files asynchronously. Manage dependency-order and nested-dependencies across versions. Detect if a resource is already loaded. Must allow for cross-domain loading (CDN's) (optional) Allow us to unload a resource. I’ve been looking at: Curl RequireJS JavaScriptMVC LABjs I might be able to fake these requirements myself by loading versions into properly-namespaced variables & using an array to track what is already loaded...but (hopefully) someone has already invented this. So my questions are: Which ones do you use? And why? Are there others that my satisfy my requirements fully? Which do you find most eloquent and easiest to work with? And why?

    Read the article

  • Unable to debug javascript?

    - by linkme69
    I’m having some problems debugging an encoded javacscript. This script I’m referring to given in this link over here. The encoding here is simple and it works by shifting the unicodes values to whatever Codekey was use during encoding. The code that does the decoding is given here in plain English below:- <script language="javascript"> function dF(s){ var s1=unescape(s.substr(0,s.length-1)); var t=''; for(i=0;i<s1.length;i++)t+=String.fromCharCode(s1.charCodeAt(i)-s.substr(s.length-1,1)); document.write(unescape(t)); } I’m interested in knowing or understanding the values (e.g s1,t). Like for example when the value of i=0 what values would the following attributes / method would hold s1.charCodeAt(i) and s.substr(s.length-1,1) The reason I’m doing this is to understand as to how a CodeKey function really works. I don’t see anything in the code above which tells it to decode on the basis of codekey value. The only thing I can point in the encoding text is the last character which is set to 1 , 2 ,3 or 4 depending upon the codekey selected during encoding process. One can verify using the link I have given above. However, to debug, I’m using firebug addon with the script running as localhost on my wamp server. I’m able to put a breakpoint on the js using firebug but I’m unable to retrieve any of the user defined parameters or functions I mentioned above. I want to know under this context what would be best way to debug this encoded js.

    Read the article

  • Slow Firefox Javascript Canvas Performance?

    - by jujumbura
    As a followup from a previous post, I have been trying to track down some slowdown I am having when drawing a scene using Javascript and the canvas element. I decided to narrow down my focus to a REALLY barebones animation that only clears the canvas and draws a single image, once per-frame. This of course runs silky smooth in Chrome, but it still stutters in Firefox. I added a simple FPS calculator, and indeed it appears that my page is typically getting an FPS in the 50's when running Firefox. This doesn't seem right to me, I must be doing something wrong here. Can anybody see anything I might be doing that is causing this drop in FPS? <!DOCTYPE HTML> <html> <head> </head> <body bgcolor=silver> <canvas id="myCanvas" width="600" height="400"></canvas> <img id="myHexagon" src="Images/Hexagon.png" style="display: none;"> <script> window.requestAnimFrame = (function(callback) { return window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame || function(callback) { window.setTimeout(callback, 1000 / 60); }; })(); var animX = 0; var frameCounter = 0; var fps = 0; var time = new Date(); function animate() { var canvas = document.getElementById("myCanvas"); var context = canvas.getContext("2d"); context.clearRect(0, 0, canvas.width, canvas.height); animX += 1; if (animX == canvas.width) { animX = 0; } var image = document.getElementById("myHexagon"); context.drawImage(image, animX, 128); context.lineWidth=1; context.fillStyle="#000000"; context.lineStyle="#ffffff"; context.font="18px sans-serif"; context.fillText("fps: " + fps, 20, 20); ++frameCounter; var currentTime = new Date(); var elapsedTimeMS = currentTime - time; if (elapsedTimeMS >= 1000) { fps = frameCounter; frameCounter = 0; time = currentTime; } // request new frame requestAnimFrame(function() { animate(); }); } window.onload = function() { animate(); }; </script> </body> </html>

    Read the article

  • Extending Currying: Partial Functions in Javascript

    - by kerry
    Last week I posted about function currying in javascript.  This week I am taking it a step further by adding the ability to call partial functions. Suppose we have a graphing application that will pull data via Ajax and perform some calculation to update a graph.  Using a method with the signature ‘updateGraph(id,value)’. To do this, we have do something like this: 1: for(var i=0;i<objects.length;i++) { 2: Ajax.request('/some/data',{id:objects[i].id},function(json) { 3: updateGraph(json.id, json.value); 4: } 5: } This works fine.  But, using this method we need to return the id in the json response from the server.  This works fine, but is not that elegant and increase network traffic. Using partial function currying we can bind the id parameter and add the second parameter later (when returning from the asynchronous call).  To do this, we will need the updated curry method.  I have added support for sending additional parameters at runtime for curried methods. 1: Function.prototype.curry = function(scope) { 2: scope = scope || window 3: var args = []; 4: for (var i=1, len = arguments.length; i < len; ++i) { 5: args.push(arguments[i]); 6: } 7: var m = this; 8: return function() { 9: for (var i=0, len = arguments.length; i < len; ++i) { 10: args.push(arguments[i]); 11: } 12: return m.apply(scope, args); 13: }; 14: } To partially curry this method we will call the curry method with the id parameter, then the request will callback on it with just the value.  Any additional parameters are appended to the method call. 1: for(var i=0;i<objects.length;i++) { 2: var id=objects[i].id; 3: Ajax.request('/some/data',{id: id}, updateGraph.curry(id)); 4: } As you can see, partial currying gives is a very useful tool and this simple method should be a part of every developer’s toolbox.

    Read the article

  • How to Enable JavaScript file API in IE8 [closed]

    - by saeed
    i have developed a web application in asp.net , there is a page in this project which user should choose a file in picture format (jpeg,jpg,bmp,...) and i want to preview image in the page but i don't want to post file to server i want to handle it in client i have done it with java scripts functions via file API but it only works in IE9 but most of costumers use IE8 the reason is that IE8 doesn't support file API is there any way to make IE8 upgrade or some patches in code behind i mean that check if the browser is IE and not support file API call a function which upgrades IE8 to IE9 automatically. i don't want to ask user to do it in message i want to do it programmatic !! even if it is possible install a special patch that is required for file API because customers thought it is a bug in my application and their computer knowledge is low what am i supposed to do with this? i also use Async File Upload Ajax Control But it post the file to server any way with ajax solution and http handler but java scripts do it all in client browser!!! following script checks the browser supports API or not <script> if (window.File && window.FileReader && window.FileList && window.Blob) document.write("<b>File API supported.</b>"); else document.write('<i>File API not supported by this browser.</i>'); </script> following scripts do the read and Load Image function readfile(e1) { var filename = e1.target.files[0]; var fr = new FileReader(); fr.onload = readerHandler; fr.readAsText(filename); } HTML code: <input type="file" id="getimage"> <fieldset><legend>Your image here</legend> <div id="imgstore"></div> </fieldset> JavaScript code: <script> function imageHandler(e2) { var store = document.getElementById('imgstore'); store.innerHTML='<img src="' + e2.target.result +'">'; } function loadimage(e1) { var filename = e1.target.files[0]; var fr = new FileReader(); fr.onload = imageHandler; fr.readAsDataURL(filename); } window.onload=function() { var x = document.getElementById("filebrowsed"); x.addEventListener('change', readfile, false); var y = document.getElementById("getimage"); y.addEventListener('change', loadimage, false); } </script>

    Read the article

  • efficient collision detection - tile based html5/javascript game

    - by Tom Burman
    Im building a basic rpg game and onto collisions/pickups etc now. Its tile based and im using html5 and javascript. i use a 2d array to create my tilemap. Im currently using a switch statement for whatever key has been pressed to move the player, inside the switch statement. I have if statements to stop the player going off the edge of the map and viewport and also if they player is about to land on a tile with tileID 3 then the player stops. Here is the statement: canvas.addEventListener('keydown', function(e) { console.log(e); var key = null; switch (e.which) { case 37: // Left if (playerX > 0) { playerX--; } if(board[playerX][playerY] == 3){ playerX++; } break; case 38: // Up if (playerY > 0) playerY--; if(board[playerX][playerY] == 3){ playerY++; } break; case 39: // Right if (playerX < worldWidth) { playerX++; } if(board[playerX][playerY] == 3){ playerX--; } break; case 40: // Down if (playerY < worldHeight) playerY++; if(board[playerX][playerY] == 3){ playerY--; } break; } viewX = playerX - Math.floor(0.5 * viewWidth); if (viewX < 0) viewX = 0; if (viewX+viewWidth > worldWidth) viewX = worldWidth - viewWidth; viewY = playerY - Math.floor(0.5 * viewHeight); if (viewY < 0) viewY = 0; if (viewY+viewHeight > worldHeight) viewY = worldHeight - viewHeight; }, false); My question is, is there a more efficient way of handling collisions, then loads of if statements for each key? The reason i ask is because i plan on having many items that the player will need to be able to pickup or not walk through like walls cliffs etc. Thanks for your time and help Tom

    Read the article

  • Creating smooth lighting transitions using tiles in HTML5/JavaScript game

    - by user12098
    I am trying to implement a lighting effect in an HTML5/JavaScript game using tile replacement. What I have now is kind of working, but the transitions do not look smooth/natural enough as the light source moves around. Here's where I am now: Right now I have a background map that has a light/shadow spectrum PNG tilesheet applied to it - going from darkest tile to completely transparent. By default the darkest tile is drawn across the entire level on launch, covering all other layers etc. I am using my predetermined tile sizes (40 x 40px) to calculate the position of each tile and store its x and y coordinates in an array. I am then spawning a transparent 40 x 40px "grid block" entity at each position in the array The engine I'm using (ImpactJS) then allows me to calculate the distance from my light source entity to every instance of this grid block entity. I can then replace the tile underneath each of those grid block tiles with a tile of the appropriate transparency. Currently I'm doing the calculation like this in each instance of the grid block entity that is spawned on the map: var dist = this.distanceTo( ig.game.player ); var percentage = 100 * dist / 960; if (percentage < 2) { // Spawns tile 64 of the shadow spectrum tilesheet at the specified position ig.game.backgroundMaps[2].setTile( this.pos.x, this.pos.y, 64 ); } else if (percentage < 4) { ig.game.backgroundMaps[2].setTile( this.pos.x, this.pos.y, 63 ); } else if (percentage < 6) { ig.game.backgroundMaps[2].setTile( this.pos.x, this.pos.y, 62 ); } // etc... (sorry about the weird spacing, I still haven't gotten the hang of pasting code in here properly) The problem is that like I said, this type of calculation does not make the light source look very natural. Tile switching looks too sharp whereas ideally they would fade in and out smoothly using the spectrum tilesheet (I copied the tilesheet from another game that manages to do this, so I know it's not a problem with the tile shades. I'm just not sure how the other game is doing it). I'm thinking that perhaps my method of using percentages to switch out tiles could be replaced with a better/more dynamic proximity forumla of some sort that would allow for smoother transitions? Might anyone have any ideas for what I can do to improve the visuals here, or a better way of calculating proximity with the information I'm collecting about each tile? (PS: I'm reposting this from Stack Overflow at someone's suggestion, sorry about the duplicate!)

    Read the article

  • LibreOffice RC1 deb package difficulties

    - by Beachbuddah
    Hi, I seem to be running into some difficulties with the acquisition of the latest libreoffice deb pkg. When I type sudo apt-get update I get E: Malformed line 60 in source list /etc/apt/sources.list (dist) E: The list of sources could not be read. I don't understand of that means that I did something wrong or if there is a problem at tuxfamily. Any help is, as always, greatly appreciated.

    Read the article

  • Practices for domain models in Javascript (with frameworks)

    - by AndyBursh
    This is a question I've to-and-fro'd with for a while, and searched for and found nothing on: what're the accepted practices surrounding duplicating domain models in Javascript for a web application, when using a framework like Backbone or Knockout? Given a web application of a non-trivial size with a set of domain models on the server side, should we duplicate these models in the web application (see the example at the bottom)? Or should we use the dynamic nature to load these models from the server? To my mind, the arguments for duplicating the models are in easing validation of fields, ensuring that fields that expected to be present are in fact present etc. My approach is to treat the client-side code like an almost separate application, doing trivial things itself and only relying on the server for data and complex operations (which require data the client-side doesn't have). I think treating the client-side code like this is akin to separation between entities from an ORM and the models used with the view in the UI layer: they may have the same fields and relate to the same domain concept, but they're distinct things. On the other hand, it seems to me that duplicating these models on the server side is a clear violation of DRY and likely to lead to differing results on the client- and server-side (where one piece gets updated but the other doesn't). To avoid this violation of DRY we can simply use Javascripts dynamism to get the field names and data from the server as and when they're neeed. So: are there any accepted guidelines around when (and when not) to repeat yourself in these situations? Or this a purely subjective thing, based on the project and developer(s)? Example Server-side model class M { int A DateTime B int C int D = (A*C) double SomeComplexCalculation = ServiceLayer.Call(); } Client-side model function M(){ this.A = ko.observable(); this.B = ko.observable(); this.C = ko.observable(); this.D = function() { return A() * C(); } this.SomeComplexCalculation = ko.observalbe(); return this; }l M.GetComplexValue = function(){ this.SomeComplexCalculation(Ajax.CallBackToServer()); }; I realise this question is quite similar to this one, but I think this is more about almost wholly untying the web application from the server, where that question is about doing this only in the case of complex calculation.

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 11 12 13 14 15 16 17 18 19 20 21 22  | Next Page >