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  Best practices of front end optimization

1. Use DocumentFragment or innerHTML to replace complex elements insertion DOM operation on browser is expensive. Although browser performance is improved much, multiple DOM elements insertion is still expensive and will affect the page load speed. Assume we have an ul element on our page, we now want to retrieve a JSON list using AJAX and then update the ul using JavaScript. Usually we may write it as : var list = document.querySelector('ul'); ajaxResult.items.forEach(function(item) { // ...

   JavaScript,Front end,Optimization,Tips     2013-07-06 11:26:27

  Avoiding and exploiting JavaScript's warts

One's sentiment toward JavaScript flips between elegance and disgust without transiting intermediate states. The key to seeing JavaScript as elegant is understanding its warts, and knowing how to avoid, work around or even exploit them. I adopted this avoid/fix/exploit approach after reading Doug Crockford's JavaScript: The Good Parts: Doug has a slightly different and more elaborate take on the bad parts and awful parts, so I'm sharing my perspective on the four issues that ha...

   JavaScript,warts,Exploit,with,variable,this     2012-02-15 05:51:21

  JavaScript: Passing by Value or by Reference

In JavaScript, we have functions and we have arguments that we pass into those functions. But how JavaScript handles what you’re passing in is not always clear. When you start getting into object-oriented development, you may find yourself perplexed over why you have access to values sometimes but not other times. When passing in a primitive type variable like a string or a number, the value is passed in by value. This means that any changes to that variable while in the function are com...

   JavaScript,Function,Pass by reference,Pa     2011-07-28 11:05:25

  Tips to improve JavaScript efficiency

Writing JavaScript code is tedious and error prone. You not only need to implement the necessary functions, but also need to ensure cross browser compatibility. This often causes the low efficiency of JavaScript developers. Here we recommend 12 tips you can benefit from. 1. Remove array element by index If we want to remove one element in an array, we can use splice. function removeByIndex(arr, index) { arr.splice(index, 1); } test = new Array(); test[0] = ’Apple’; test[1] = &rsq...

   JavaScript,Tips,Array     2013-07-27 20:50:40

  5 Reasons Your Javascript Stinks

Javascript gets a bad rap on the Internet, but there are few languages that are so dynamic, so widespread, and so deeply rooted in our lives as Javascript is. The low barrier of entry leads some people to call it a script kiddie language, others scoff at the concept of a dynamic language while riding their statically typed high horse. You and Javascript just got off on the wrong foot, and now you've made it angry. Here's five reasons why your Javascript code sucks.1. You're not using a namespace...

   JavaScript,Good,Habit,Prototype,OOP     2011-04-13 12:25:37

  Program Or Be Programmed

On Thursday night I gave a talk at NYU Poly and in the Q&A a young man asked me for advice for "those who aren't technical". I said he should try to get technical. The next morning I met with a bunch of Sloan Business School students doing a trek through NYC. A young woman asked me the same question. I gave her the same answer.I don't mean that everyone should become a software engineer. I do mean that everyone should understand software engineering (or whatever technical...

   Program,Technical,Basic knowledge     2011-11-10 10:31:02

  So you want to write JavaScript for a living?

What do you need to know if you are interviewing for a job that involves Javascript development? What kind of expectations do employers have of candidates now that the state of client side development has been changed with the rise of asynchronous JavaScript and the often slick, supporting interfaces? These were questions I was asking myself after a friend pointed me to an interesting job posting over at Meebo that included some JavaScript puzzlers on logical operators, DOM odditi...

   JavaScript,Career,Skills,Knowledge     2011-10-22 12:53:11

  10 reasons why Dart is cooler than JavaScript

Dart is a new programming language from Google and after coding JavaScript for over one year now, I immediately felt in love with it. Coming from the Java world I had a good bunch of things I had to learn before I could use JavaScript. Some people say, you need to dig deep into JavaScript, otherwise you are not allowed to speak about the pros and cons of a language. I am not a JavaScript Ninja. But I strongly believe a programming language should be easy to learn, easy to understand and s...

   Dart,JavaScript,Comparison     2012-01-05 08:23:21

  Cool HTML5 matrix effect

Do you still remember the movie The Matrix? Do you still remember the cool matrix effect in that movie? How is that effect achieved? Shaun Dunne shared a piece of HTML5 code which displays a cool matrix effect. The matrix demo can be found here. Below is the code which he achieves this effect: with var s = window.screen; var width = q.width = s.width; var height = q.height = s.height; var letters = Array(256).join(1).split(''); var draw = function () { q.getContext('2d').fillStyle='rgba(0,0,...

   Matrix,HTML5     2013-08-14 08:03:34

  Using C for a specialized data store

Pixenomics stores and transports 1.2 million pixels from the server to the client. During development we played with various methods to store and process this. Our ultimate goal was to send the entire board in under 1 second. During the stages of prototyping we used a MySQL database without thinking too much about performance. With a mere 2,000 pixels we quickly realised this wasn’t even usable as a demo. Changing the storage engine to memory was much better but still obviously unu...

   C,Data store,Efficiency,Performance     2012-03-07 05:09:38

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