JavaScript 2.0 Compatibility

Thursday, November 11, 1999

JavaScript 2.0 is intended to be upwards compatible with JavaScript 1.5 and earlier scripts. The following are the current compatibility issues:

• Replace void expr by void(expr).
• Replace expr[expr, expr] by expr[(expr, expr)] because commas are now significant inside brackets.
• Rename uses of eval for identifiers.
• Code that modifies the standard JavaScript 1.5 objects such as Object and String may not work.

JavaScript 2.0 is still evolving, and some of these compatibility issues may be addressed as the language matures. They are not expected to be a problem in practice because a browser could distinguish JavaScript 1.5 and earlier scripts from JavaScript 2.0 scripts and behave compatibly on the earlier ones.

Waldemar Horwat Last modified Thursday, November 11, 1999