Understanding ECMAScript versioning
ECMAScript is the formal standard for the JavaScript language. The first three iterations of the language occurred between 1997 and 1999. A 10-year gap followed before ECMAScript 5 in December 2009. ES5 introduced few new features and focused on cleaning up the language. It introduced strict modes and addressed various inconsistencies, flaws, or gotchas in earlier versions.
2015 saw a major change to the language and to the versioning approach. ECMAScript 2015 (formerly ECMAScript 6) introduced many significant new language features. These include classes, let/const keywords and block-scoping, arrow functions, and native promises. In the rest of this chapter, we'll look at some of the other significant new features in ES2015.
The name change from ES6 to ES2015 indicates a new yearly versioning model. From 2015 onwards, there will be a new version of the ECMAScript standard every year. Planned features that aren't quite ready for release will wait...
