Both Microsoft and Netscape have continued to enhance their implementations in subsequent versions of their web browsers, taking them sometimes in completely opposing directions.
In November 1996, the language started to become standardized by a working group under the ECMA organization. At this stage it was also commonly referred to as ECMAScript and became a published standard in June 1997. By April 1998, the ECMA 262 standard had been adopted as an international standard as ISO/IEC 16262 which prompted a second edition of the ECMA standard to keep the two fully aligned.
A third edition of the ECMA 262 standard was published in October 1999.
ECMA 262 edition 2 - section - Introduction
ECMA 262 edition 3 - section - Introduction