Описание тега ecmascript-5
In 1995 Brendan Eich of Netscape invented a scripting language JavaScript for the Netscape browser. One year later Microsoft developed a compatible dialect of the language, JScript. Lately flash platform implemented its ActionScript language based in the same standard.
Netscape delivered JavaScript to Ecma International for standardization which started the process as EcmaScript in the Ecma-262 Standard in November 1996 (5).
ECMAScript-5 is an update of the EMCAScript-262 3rd edition specification after the cancellation of the 4th edition. It adds new features including strict mode, getters and setters, a JSON object, and new methods for Object, Array, Date, and Function prototypes.
Articles covering the new specification in detail are available e.g. on infoq.com and the Opera Dev Channel.
This compatibility table covers the Browser support of EcmaScript 5.