History of JavaScript
JavaScript, not to be confused with Java, was created in 10 days in May 1995 by Brendan Eich, then working at Netscape and now of Mozilla. JavaScript was not always known as JavaScript: the original name was Mocha, a name chosen by Marc Andreessen, founder of Netscape. In September of 1995 the name was changed to LiveScript, then in December of the same year, upon receiving a trademark license from Sun, the name JavaScript was adopted. This was somewhat of a marketing move at the time, with Java being very popular around then.
In 1996 - 1997 JavaScript was taken to ECMA to carve out a standard specification, which other browser vendors could then implement based on the work done at Netscape. The work done over this period of time eventually led to the official release of ECMA-262 Ed.1: ECMAScript is the name of the official standard, with JavaScript being the most well known of the implementations. ActionScript 3 is another well-known implementation of ECMAScript, with extensions (see below).
The standards process continued in cycles, with releases of ECMAScript 2 in 1998 and ECMAScript 3 in 1999, which is the baseline for modern day JavaScript. The "JS2" or "original ES4" work led by Waldemar Horwat (then of Netscape, now at Google) started in 2000 and at first, Microsoft seemed to participate and even implemented some of the proposals in their JScript.net language.
Over time it was clear though that Microsoft had no intention of cooperating or implementing proper JS in IE, even though they had no competing proposal and they had a partial (and diverged at this point) implementation on the .NET server side. So by 2003 the JS2/original-ES4 work was mothballed.
The next major event was in 2005, with two major happenings in JavaScript’s history. First, Brendan Eich and Mozilla rejoined Ecma as a not-for-profit member and work started on E4X, ECMA-357, which came from ex-Microsoft employees at BEA (originally acquired as Crossgain). This led to working jointly with Macromedia, who were implementing E4X in ActionScript 3(ActionScript 3 was a fork of Waldemar's JS2/original-ES4 work).
So, along with Macromedia (later acquired by Adobe), work restarted on ECMAScript 4 with the goal of standardizing what was in AS3 and implementing it in SpiderMonkey. To this end, Adobe released the "AVM2", code named Tamarin, as an open source project. But Tamarin and AS3 were too different from web JavaScript to converge, as was realized by the parties in 2007 and 2008.