JavaScript のリテラルパターン - A Memorandum
オブジェクトリテラル オブジェクトの作成はコンストラクタにて以下のように書けます。 var car = new Object(); car.goes = "far"; が、より簡素なオブジェクトリテラル表記を使うべきです。 var car = {goes: "far"}; オブジェクトコンストラクタに数値を渡した場合、以下のように実際に作成されるオブジェクトが異なります。 var o1 = new Object(2); console.log(o1.constructor === Number); // true var o2 = new Object("hello"); console.log(o2.constructor === String); // true var o3 = new Object(true); console.log(o3.constructor === Bool
John Resig - Learning from Twitter
An issue popped up on Twitter this past week that caused the web site to be generally unusable for many users. It appears as if attempts to scroll were unbearably slow and caused the site to be unresponsive. The Twitter team investigated and determined that if they reverted the version of jQuery that they used back to 1.4.2 from 1.4.4 the site would be responsive again. After more investigation th
Building Large-Scale jQuery Applications
December 24, 2010 Today we're going to look at the end-to-end tools and options you have for building large-scale enterprise jQuery applications. Although jQuery is an excellent JavaScript library and provides a well-designed set of tools for development, it's focus on staying compact and making the DOM easy to use has meant that it doesn't provide a significant infrastructure for building large-s
DTrace, node.js and the Robinson Projection – The Observation Deck
When I joined Joyent, I mentioned that I was seeking to apply DTrace to the cloud, and that I was particularly excited about the development of node.js — leaving it implict that the intersection of the two technologies would be naturally interesting, As it turns out, we have had an early opportunity to show the potential here: as you might have seen, the Node Knockout programming contest was held
JavaScript: Bad Practices – James Padolsey
I’ve seen a lot of curious (bordering on horrific) code in my life; and I’d say about half of it was written by me. If you don’t attest to the fact that you once wrote crap code then you’re either a liar or perhaps, have omnipotent powers! Here’s a relatively small collection of what I see as bad JavaScript practices; in other words – a list of how to write really really ugly JavaScript that will
Ending The ga.js Wait | Continuing Intermittent Incoherency
Google Analytics is ubiquitous, not least of all because it’s better at what it does than most of the alternatives. Also, it doesn’t require any install or maintenance. And it’s free. What’s not to like? Frankly, not much, but if I had to nit pick, I’d note that the worst part of Google Analytics is the ga.js script that does the actual tracking of content. It’s not bad, in and of itself, but it t
Javascript Best Practices
The document outlines best practices for JavaScript development, emphasizing clarity, modularity, and performance. Key recommendations include avoiding global variables, minimizing DOM access, using descriptive variable names, and not mixing technologies. It also stresses the importance of writing maintainable and understandable code while utilizing libraries to streamline development.
Speed up your JavaScript, Part 4 - Human Who Codes
Posted at February 3, 2009 by Nicholas C. Zakas Tags: DOM, JavaScript, Performance, Reflow Over the past few weeks, I’ve been exploring the various techniques for speeding up your JavaScript. Part 1 covered how to deal with loops that are doing too much. Part 2 focused on functions that do too much and taught techniques such as queuing and memoization to lighten the workload. Part 3 expanded the c
Speed up your JavaScript, Part 3 - Human Who Codes
Posted at January 27, 2009 by Nicholas C. Zakas Tags: Iteration, JavaScript, Memoization, Performance, Recursion Recursion is the enemy of fast-running scripts. Too much recursion can cause the browser to grind to a halt or quit unexpectedly, and so must be addressed a serious performance problem in JavaScript. In part 2 of this series, I wrote briefly about handling too much recursion in a functi
Speed up your JavaScript, Part 2 - Human Who Codes
Posted at January 20, 2009 by Nicholas C. Zakas Tags: JavaScript, Loops, Memoization, Performance, Recursion Last week, I covered the first reason why JavaScript can take too long to execute: too much happening in a loop. There’s a similar problem with functions in that sometimes they’re just doing too much. Usually this means there’s too many loops (as opposed to too much happening in a loop), to
Speed up your JavaScript, Part 1 - Human Who Codes
In my last post, I talked about the conditions under which the dreaded long-running script dialog is displayed in browsers. Browsers will stop executing script either when they’ve executed too many statements (Internet Explorer) or when the JavaScript engine has been running for a specific amount of time (others). The problem, of course, isn’t the way that the browser is detecting long-running scr
for 文と無名関数のイディオム - IT戦記
id:cho45 がチョロっと書いたコードが話題になっている 冬通りに消え行く制服ガールは✖夢物語にリアルを求めない。 - subtech このような書き方は、自分もたまにする。 というわけで、この書き方をする利点を以下の順に解説して見る。 単純な for 文の問題点 with 文を使った解決方法と、その微妙な問題点 無名関数を使った解決方法 単純な for 文の問題点 まずは、以下の HTML に対して <ul> <li>hoge</li> <li>fuga</li> <li>piyo</li> </ul> 以下の JavaScript を実行して var list = document.querySelectorAll('ul > li'); for (var i = 0, len = list.length; i < len; i++) { var node = list[i]; v
Google Chrome JavaScriptデバッガ完全マニュアル。 - IT-Walker on hatena
Google Chromeはシンプルに見えてオフラインやWebアプリショートカット作成などいろんな機能が搭載されています。 そんな中、JavaScriptデバッガがあるのも発見！ どんなもんかと思ってみてみたら、なんとコマンドラインベースのデバッガです。Firebugみたいな物を想定していたのですが、まさかgdb（GNU製C/C++デバッガ）みたいなのがブラウザに載ってるなんて・・・しかも全然情報ないし。 でも開発者にとっては、JavaScriptをランタイムでデバッグできると言うのは非常に嬉しい事ですね。そこで、Chromeデバッガの使用法についてちょっと調べてみました。 デバッガは、開発者向けメニューの中から選択する事が出来ます。立ち上げてみると、コマンドの表示結果が表示されるエリアと、コマンドを入力するテキストフィールドが並んでいるだけ、と言うシンプルなUIが表示されます。 最下部の
tralfamadore.com: Xsstc: Cross-site scripting through CSS
I've been doing a lot of reading on cross-domain scripting approaches. Generally speaking, the browser is sandboxed by the same-origin policy, and mashups that want to incorporate data from external sites, even if those sites are cooperating, need to provide server-side proxies. There are a couple of popular workarounds: (1) using the hash (#) portion of the URL, which can be read between frames,
二度押し防止の onsubmit で disable にするやつ :: Drk7jp
もう２年ほど前に話題になったアレなんですけど、今更ながらあるサービスでこの仕組みの導入を検討しています。 onsubmit で submit ボタンを disable にしてユーザビリティを良くする - naoyaのはてなダイアリー submit ボタン disable 技の罠 - naoyaのはてなダイアリー onsubmit で submit ボタンを < disable にしてユーザビリティを悪くするのはやめてください - のヮの うんこ♥ onsubmit で disable にするやつ - 鷹の島 onsubmit の disable 化ですが既に議論が終わっているように、onsubmit disable の実装方法として、 onsubmit イベント発生時に submit 要素を disable にして値をサーバへ渡すための hidden 要素を生成する方法 setTimeou
Yahoo!'s Latest Performance Breakthroughs (Yahoo! Developer Network Blog)
March 17, 2008 Stoyan Stefanov made an appearance last week at the PHP Quebec Conference in Montreal. His session debuts Yahoo!’s latest research results and performance breakthroughs. He covers the existing 14 rules, plus 20 new rules for faster web pages. We’ve categorized the optimizations into: server, content, cookie, JavaScript, CSS, images, and mobile. After YSlow "A"? If your page isn't ge
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http://www.thewojogroup.com/2008/10/10-easy-steps-to-great-website-optimization/
http://webjackalope.com/fast-page-load-time/
Introducing Multithreaded Programming to JavaScript
http://www.hedgerwow.com/360/dhtml/ie6_memory_leak_fix/