The following is a changelog for JavaScript 1.5. This version was included in Netscape Navigator 6.0 was released on November 14, 2000 and was also used in later versions of Netscape Navigator and Firefox 1.0. You can compare JavaScript 1.5 to JScript version 5.5 and Internet Explorer 5.5, which was released in July 2000. The corresponding ECMA standard is ECMA-262 Edition 3 (from December 1999).

New features in JavaScript 1.5

• Number.prototype.toExponential()
• Number.prototype.toFixed()
• Number.prototype.toPrecision()
• const is now a reserved word.
• Multiple catch clauses in a try...catch statement are supported.
• JavaScript authors can now add getters and setters to their objects.

Changed functionality in JavaScript 1.5

• Runtime errors are now reported as exceptions.
• Regular Expression changes:
  • Quantifiers — +, *, ? and {} — can now be followed by a ? to force them to be non-greedy.
  • Non-capturing parentheses, (?:x) can be used instead of capturing parentheses, (x). When non-capturing parentheses are used, matched subexpressions are not available as back-references.
  • Positive and negative lookahead assertions are supported. Both assert a match depending on what follows the string being matched.
  • The m flag has been added to specify that the regular expression should match over multiple lines.
• Functions can now be declared inside an if clause.

• Functions can now be declared inside an expression.