1998 — Macromedia Inc (now part of Adobe Systems) created something similar called ActionScript. The last stable release was in 2006. No one talks about ActionScript anymore since the death of Flash and is considered a dialect of ECMAScript.
ES1 (June 1997), ES2 (June 1998), ES3 (Dec 1999), ES4 (Abandoned) — are the first 4 editions of ECMAScript. We don’t really need to know the details of these because programming seems to age in dog years and these versions can now be considered ancient.
ES 5 (December 2009) — ten years after politics resulted in the abandonment of ES4, ES5 was released.
ES6 / ES2015 (June 2015) — ES6 was the name popularized before release but came out under the name ES2015 to reflect the year it was released. This means that ES6 and ES2015 are the same thing. Officially its called ES2015 but most people know it as ES6.
ES2016 (ES7 / June 2016), ES2017 (ES8 / June 2017), ES2018 (ES9 / June 2018) — New versions of ECMAScript has now moved to yearly revisions and releases. Don’t worry, everything is backward compatible and new features such as asynchronous iteration and generators, regular expression features and rest/spread parameters have been added to make life easier.
June 2019? — flattening arrays through
Array.prototype.flat() and optional catch binding is currently on the table for ES2019. There’s still 3-ish months away before the new features is available to us.