Chrome gets sneak peek of "Harmony" JavaScript features

Google has announced that the development channel version of Chrome now has support for "Harmony" JavaScript features. "Harmony" is the name of the major upgrade to JavaScript due to arrive by the end of 2013. In 2008, after much controversy, the ECMA Technical Committee 39, that had been charged with creating the next generation of JavaScript, agreed to work together on a "Harmony" update to JavaScript and it has been in development since then.

A number of the proposed features of Harmony are supported by Google's implementation. These include block scoped bindings and the addition of the let keyword, efficient maps and sets to remove the need to "abuse objects as dictionaries", weak maps for garbage collectable key/value tables and proxies which can simulate any JavaScript object or function to enable customisation.

The work is being done in conjunction with the V8 JavaScript engine development team. To make use of the features, users will need the dev channel version of Chrome: go to chrome://flags and toggle "Experimental JavaScript Features". Given that no production browser supports these features, users should be aware that this is only for evaluation and testing and should not make use of the new language features in production code.

(djwm)