The General Assembly of Ecma International announced the approval of ECMA-262 6th Edition, the new version of the standard on which JavaScript is based. The official name of this latest version is ECMAScript 2015. ES6 adds many basic features such as modules and classes, and some more useful as maps or sets of generators . In addition to being a significant improvement , ES6 is fully compatible with previous versions. It will take some time to see the major browsers implement fully the ES6 features, perhaps even more than one year.
More interesting details on ES6: Article from Carlos Azaustre
Sources: ECMA International, TC39 Process (Google Docs)