February 1999 Draft
JavaScript 2.0

Thursday, February 18, 1999

JavaScript 1.x

Existing JavaScript 1.x scripts will continue to run in a browser environment because browsers will be able to distinguish JavaScript 2.0 or later scripts from JavaScript 1.x scripts and treat each script according to the language in which it was written. JavaScript 2.0 scripts can be distinguished as follows:


Some developers will want to incrementally modify their JavaScript 1.x scripts to take advantage of JavaScript 2.0 features. Many JavaScript 1.x scripts are compatible and will run unchanged in either JavaScript 1.x or JavaScript 2.0 (as long as one changes the language attribute or adds an import statement). The vast majority of other JavaScript 1.x scripts can be made compatible via the following process, which can be performed automatically:

We intend to provide a tool that will perform such transformations.

The main situations where manual intervention may be required are:

Waldemar Horwat
Last modified Thursday, February 18, 1999