Harmony Collections
Simple maps and sets allow you to create a Map with an object as the key. Normally people use Object.create(null) as a map but that limits the keys to strings. The Set constructor is similar and it...
View ArticleProxies
V8 currently implements the same Proxy API as Firefox. The API for proxies has changed a bit since then so be extra careful when testing this. Proxies are a very low lever construct. The are very...
View ArticleJavaScript Harmony in Chrome
We recently added a way to turn on JavaScript Harmony features in Chrome. If you have a Canary or a recent Developer Channel build of Chrome you can turn on some Harmony features from chrome://flags....
View ArticleIterating over Harmony Maps
A while ago Chrome got some JavaScript Harmony features (behind a flag). One of these features is the new Map “class”. The current implementation does not provide a way to iterate over the keys or...
View ArticleBlock Scope
Did you know that ES5.1 does not support function declarations inside blocks? Browsers do allow it but they do not agree on the semantics. For ES Harmony we are specifying the semantics for functions...
View ArticleAdding transformation passes to Traceur Compiler
Traceur Compiler is an open source ES.next to ES5 compiler. We released it a while back but today I finished writing a tutorial about how to add new transformation passes. As you can see it is pretty...
View ArticleClosure
Today we finally announced and released Closure (or Closure Library as the JS library is officially known as). History Me and Dan Pupius started the JS library at Google a long time ago. At the time...
View ArticleEcmaScript Edition 5 is final
After a lot of back and forth in the TC and the failure of ES4 the TC was focused on ES3.1. The final spec for ES3.1 is now called EcmaScript, Fifth Edition. The most exciting thing in ES5 is that it...
View ArticleInheritance Antipattern
Michael Bolin wrote an excellent blog post about the inheritance antipattern that is gaining a lot of foothold among JavaScript developers these days. The post also links to an article giving a lot...
View Articletypeof null
In ES5 typeof null evaluates to 'object'. This quirk was one of the changes we wanted to fix in ES5 but at the time we agreed that we did not want any semantic changes. With Harmony there will be a way...
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