Versioning

The JavaScript standard is referred to officially as “ECMAScript” (abbreviated “ES”), and up until just recently has been versioned entirely by ordinal number (i.e., “5” for “5th edition”).

The earliest versions, ES1 and ES2, were not widely known or implemented. ES3 was the first widespread baseline for JavaScript, and constitutes the JavaScript standard for browsers like IE6-8 and older Android 2.x mobile browsers. For political reasons beyond what we’ll cover here, the ill-fated ES4 never came about.

In 2009, ES5 was officially finalized (later ES5.1 in 2011), and settled as the widespread standard for JS for the modern revolution and explosion of browsers, such as Firefox, Chrome, Opera, Safari, and many others.

Leading up to the expected next version of JS (slipped from 2013 to 2014 and then 2015), the obvious and common label in discourse has been ES6.

However, late into the ES6 specification timeline, suggestions have surfaced that versioning may in the future switch to a year-based schema, such as ES2016 (aka ES7) to refer to whatever version of the specification is finalized before the end of 2016. Some disagree, but ES6 will likely maintain its dominant mindshare over the late-change substitute ES2015. However, ES2016 may in fact signal the new year-based schema.

It has also been observed that the pace of JS evolution is much faster even than single-year versioning. As soon as an idea begins to progress through standards discussions, browsers start prototyping the feature, and early adopters start experimenting with the code.

Usually well before there’s an official stamp of approval, a feature is de facto standardized by virtue of this early engine/tooling prototyping. So it’s also valid to consider the future of JS versioning to be per-feature rather than per-arbitrary-collection-of-major-features (as it is now) or even per-year (as it may become).

The takeaway is that the version labels stop being as important, and JavaScript starts to be seen more as an evergreen, living standard. The best way to cope with this is to stop thinking about your code base as being “ES6-based,” for instance, and instead consider it feature by feature for support.