JavaScript Versions

Question: What JavaScript versions are there?

Answer: JavaScript is one of the youngest programming languages. It was first implemented by Netscape Communications in 1995. The first browser to support JavaScript was Netscape Navigator 2.0 beta version. By 1999 the two major browsers, Netscape Navigator and Microsoft Internet Explorer, supported the following client-side versions of JavaScript:

Browser Year JavaScript Version
Netscape Navigator 2.0 1995 JavaScript 1.0
Microsoft Internet Explorer 3.0 1996 JavaScript 1.0 (JScript 1.0)
Netscape Navigator 3.0 1996 JavaScript 1.1
Netscape Navigator 4.0 1997 JavaScript 1.2
Microsoft Internet Explorer 4.0 1997 JavaScript 1.2 (JScript 3.0)
Netscape Navigator 4.5 1998 JavaScript 1.3
Microsoft Internet Explorer 5.0 1999 JavaScript 1.3 (JScript 5.0)

Unfortunately, Netscape and Microsoft implementations of JavaScript are different, even for the same JavaScript version number. For example, JavaScript 1.0 in Internet Explorer 3 differs from JavaScript 1.0 in Netscape Navigator 2; similarly, JavaScript 1.2 in Internet Explorer 4 is not the same as JavaScript 1.2 in Netscape Navigator 4.

In addition to these JavaScript versions, third parties can also create their own JavaScript implementations, or license the JavaScript technology from either Microsoft or Netscape. For example, the Opera browsers now support JavaScript.

What does that mean for cross-platform coding? Essentially, you have to use either of the following two techniques (or combine both):