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JavaScript Versions


JavaScript was invented by Brendan Eich in 1995, and became an ECMA standard in 1997.
ECMA-262 is the official name of the standard. ECMAScript is the official name of the language.


ECMAScript Editions

Year Name Description
1997 ECMAScript 1 First Edition.
1998 ECMAScript 2 Editorial changes only.
1999 ECMAScript 3 Added Regular Expressions.
Added try/catch.
ECMAScript 4 Was never released.
2009 ECMAScript 5 Added “strict mode”.
Added JSON support.
2011 ECMAScript 5.1 Editorial changes.
2015 ECMAScript 6 Added classes and modules.
2016 ECMAScript 7 Added exponential operator (**).
Added Array.prototype.includes.

ECMAScript 6 is also called ECMAScript 2015.

ECMAScript 7 is also called ECMAScript 2016.


Browser Support

ECMAScript 3 is fully supported in all browsers.

ECMAScript 5 is fully supported in all modern browsers*.

ECMAScript 6 is partially supported in all modern browsers.

ECMAScript 7 is poorly supported in all browsers.

* Internet Explorer 9 does not support ECMAScript 5 “use strict”.



ECMAScript Browser Implementations

Engine ECMA Browser
V8 6 Chrome (Partial Support)
SpiderMonkey 6 Firefox (Partial Support)
Chakra 6 Edge (Partial Support)
Nitro 6 Safari (Partial Support)
V8 6 Opera (Partial Support)
V8 5 Chrome 23
SpiderMonkey 5 Firefox 21
JavaScript 1.8.5 5 Firefox 4
Nitro 5 Safari 6
V8 5 Opera 15
Chakra 5 Edge 12
Chakra 5 IE 10

JavaScript / ECMAScript / JScript

JavaScript was developed for Netscape. The first browser to run JavaScript was Netscape 2 in 1996. After Netscape the Mozilla foundation continued to develop JavaScript for the Firefox browser. JavaScript version numbers run from 1.0 to 1.8.

ECMAScript was developed by Ecma International after the organization adopted JavaScript. The first edition of ECMAScript was released in 1997. ECMAScript version numbers run from 1 to 7.

JScript was developed by Microsoft as a compatible JavaScript language for Internet Explorer in 1996. JScript version numbers runs from 1.0 to 9.0.

This list compares the version numbers of the three different products:

Year JavaScript ECMA JScript Browser
1996 1.0 Netscape 2
1996 1.0 Internet Explorer 3
1996 1.1 Netscape 3
1997 1.2 Netscape 4
1997 1 3.0 Internet Explorer 4
1998 1.3 1 Netscape 4.06
1999 2 5.0 Internet Explorer 5
1999 2 5.1 Internet Explorer 5.1
2000 3 5.5 Internet Explorer 5.5
2000 1.5 3 Netscape 6
2000 1.5 3 Firefox 1
2001 3 5.6 Internet Explorer 6
2006 3 5.7 Internet Explorer 7
2005 1.6 3 Firefox 1.5
2006 1.7 3 Firefox 2
2008 1.8 3 Firefox 3
2009 3 5.8 Internet Explorer 8
2009 1.8.1 5 Firefox 3.5 (Partial Support)
2009 1.8.2 5 Firefox 3.6 (Partial Support)
2011 1.8.5 5 Firefox 4
2011 5 9.0 Internet Explorer 9 (Partial Support)

Internet Explorer 4 (JScript 3.0) and Netscape 4.06 (JavaScript 1.3) were the first browsers to support ECMAScript 1.

Internet Explorer 5 (JScript 5.0) was the first browser to support ECMAScript 2.

Internet Explorer 5.5 (JScript 5.5) and Netscape 6 (JavaScript 1.5) were the first browsers to support ECMAScript 3.

Internet Explorer 9 (JScript 9.0) and Firefox 3.5 (JavaScript 1.8.1) were the first browsers to support ECMAScript 5.