Google Closure: How not to write JavaScript At the Edge of the Web conference in Perth last week I got to catch up with Dmitry Baranovskiy, the creator of the Raphaël and gRaphaël JavaScript libraries. Perhaps the most important thing these libraries do is make sophisticated vector graphics possible in Internet Explorer, where JavaScript performance is relatively poor. Dmitry, therefore, has little patience for poorly-written JavaScript like the code he found in Google’s just-released Closure Library. Having delivered a talk on how to write your own JavaScript library (detailed notes) at the conference, Dmitry shared his thoughts on the new library over breakfast the next morning. “Just what the world needs—another sucky JavaScript library,” he said. For the rest of the day, to anyone who would listen, Dmitry cited example after example of the terrible code he had found when he went digging through Closure. “I’ll make you a deal,” I told him. The Slow Loop From array.js, line 63: for (var i = fromIndex; i < arr.length; i++) {
A JavaScript Module Pattern Eric Miraglia (@miraglia) is an engineering manager for the YUI project at Yahoo. Eric has been at Yahoo since 2003, working on projects ranging from Yahoo Sports to YUI. For the past several years, Eric and his colleagues on the YUI team have worked to establish YUI as the foundation for Yahoo’s frontend engineering work while open-sourcing the project and sharing it with the world under a liberal BSD license. Eric is an editor and frequent contributor to YUIBlog; his personal blog is at ericmiraglia.com. Prior to working at Yahoo, Eric taught writing at Stanford and elsewhere and led frontend engineering teams at several startups. Global variables are evil. Douglas Crockford has been teaching a useful singleton pattern for achieving this discipline, and I thought his pattern might be of interest to those of you building on top of YUI. 1. YAHOO.namespace("myProject"); This assigns an empty object myProject as a member of YAHOO (but doesn’t overwrite myProject if it already exists). 2.
css3-mediaqueries-js - Project Hosting on Google Code css3-mediaqueries.js by Wouter van der Graaf is a JavaScript library to make IE 5+, Firefox 1+ and Safari 2 transparently parse, test and apply CSS3 Media Queries. Firefox 3.5+, Opera 7+, Safari 3+ and Chrome already offer native support. UPDATE: Google discontinued the downloads section. Download newest version 1.0 from here: Usage: just include the script in your pages. (And you should combine and compress with other scripts and include it just before </body> for better page speed - but you already knew that). Write your media queries like you would for browsers with native support. Note: Doesn't work on @import'ed stylesheets (which you shouldn't use anyway for performance reasons). Happy media querying!
Understanding JavaScript’s this keyword | JavaScript, JavaScript (In Portugese) The JavaScript this keyword is ubiquitous yet misconceptions abound. What you need to know Every execution context has an associated ThisBinding whose lifespan is equal to that of the execution context and whose value is constant. There are three types of execution context: global, function and evaluation. Here’s a tabular summary followed by a little more detail, and some examples: 1. 2. a) Invoke as a methodthis is the baseValue of the property reference b) Invoke as baseless function callthis is the global object (or undefined in strict mode) The same applies to self invoking functions: c) Invoke using Function.prototype.callthisis passed by argument d) Invoke using Function.prototype.applythis is passed by argument e) Invoke a constructor using newthis is the newly created object 3. What you might want to know This section explores the process by which this gets its value in the functional context – using ECMA-262 version 5.1 as a reference. from ECMA 5.1, 11.1.1 1. 1. In full…
base2 - Project Hosting on Google Code Because this library is standards-based it means that you don’t have to learn a new API. It uses standard (DOM, ECMAScript) properties and methods throughout which also means that there is no need for a lot of accompanying documentation. base2 is a lightweight library that irons out all the annoying differences in JavaScript implementations. It provides the additional functionality from JavaScript 1.6+ that only Mozilla browsers implement. It also adds some features from ES4. A fast implementation of the Selectors API Fixes broken browser implementations of the DOM events module including document.createEvent(), dispatchEvent(), addEventListener(), etc Supports DOMContentLoaded Fixes getAttribute()/setAttribute()/hasAttribute() (Internet Explorer) Implements getElementsByClassName() Implements a few other useful DOM methods like getComputedStyle() and compareDocumentPosition() Supports a variety of browsers including ancient browsers like IE5.0 (Windows and Mac) Current version: 1.0.2
Sylvester - Vector and Matrix math for JavaScript Badass JavaScript evercookie - virtually irrevocable persistent cookies samy's home page || follow my twitter || email me || samy kamkar October 11, 2010: Reported on the front page of the New York Times Find the latest details, code, and implementations on github @ Cookie found: uid = currently not set Click to create an evercookie. Don't worry, the cookie is a random number between 1 and 1000, not enough for me to track you, just enough to test evercookies. Now, try deleting this "uid" cookie anywhere possible, then or evercookie is written in JavaScript and contains portions in Java, SWF/ActionScript (Flash) and C# (Silverlight). What is the point of evercookie? csshack, best website ever See CONTACT. Questions or comments, email me: code@samy.pl.
37signals' Chalk Dissected Update 2010-11-05: I dove into the JavaScript a little and explained most of it. Sam Stephenson tweeted that Chalk is written in CoffeeScript and compiled on the fly when served using Brochure. That's hot! (for those unaware Sam Stephenson works at 37signals, and is also the man behind Prototype.) 37signals recently released a blackboard web app for iPad called Chalk. It includes Thomas Fuchs new mobile JS framework Zepto, a few images, iOS SpringBoard icon, and of course HTML, CSS, and JavaScript. The manifest is a nice summary of the contents, and allows browsers to cache the app for offline use. CACHE MANIFEST / /zepto.min.js /chalk.js /images/background.jpg /images/chalk.png /images/chalk-sprites.png /images/chalk-tile-erase.jpg /images/chalk-tile-red.png /images/chalk-tile-white.png /stylesheets/chalk.css Not much there, just 10 requests to fetch the whole thing. 11 including the manifest. 2k, 61 lines. 10 of which are Google Analytics JavaScript. Onward. Zepto Display (CSS & Images)
batiste/sprite.js - GitHub Face Detection jQuery Plugin audio.js It uses native <audio> where available and an invisible flash player to emulate <audio> for other browsers. It provides a consistent html player UI to all browsers which can be styled used standard css. Installation Put audio.js, player-graphics.gif & audiojs.swf in the same folder. Examples A series of API tests & examples for using and extending audio.js Example 1 Test multiple load types Example 2 Custom markup/css Example 3 Multiple players, testing preload, loop & autoplay attributes Example 4 Customised player Example 5 Customised playlist player Browser & format support With Flash as a fallback, it should work pretty much anywhere. Mobile Safari (iOS 3+) Android (2.2+, w/Flash) Safari (4+) Chrome (7+) Firefox (3+, w/ Flash) Opera (10+, w/ Flash) IE (6, 7, 8, w/ Flash) ogg audio.js focuses on playing mp3s. Flash local security Source code All efforts have been made to keep the source as clean and readable as possible. Annotated source / Source on Github License Documentation Translations
What to Read to Get Up to Speed in JavaScript There’s a discussion going on on the JSMentors JavaScript mailing list about books to read to get you to the next level . There’s been a lot of great feedback and suggestions thrown out and I wanted to offer up what I felt were good to carry you through the learning process. While I list a number of books in the Big List page that I created , narrowing it down into specific levels makes a lot of sense. Note that some resources will overlap between levels. That should be expected as some books cover a wide breadth of language features. Also, I am NOT covering blogs in this post, only books (print and online). These are books that I’ve read over the years and found incredibly useful so I’m categorizing them to make it easier for you to get going. Introductory These are books that will give you the fundamentals of the JavaScript language and get you started: JavaScript: The Good Parts Professional JavaScript for Web Developers (Wrox Programmer to Programmer) ppk on JavaScript, 1/e Intermediate