Dynamic HTML: The Definitive Reference

Name

!= — NN 2 IE J1 ECMA 1

Synopsis

The inequality operator. This operator compares two operand values and returns a Boolean result. The behavior of this operator differs with the version of JavaScript specified for the SCRIPT element. If the LANGUAGE attribute is set to JavaScript or JavaScript1.1, some operands are automatically converted as for the equality (==) operator. Version 1 of ECMAScript observes the same behavior. The situation is a bit different in Navigator when the SCRIPT element is set to LANGUAGE="JavaScript1.2". The browser is more literal about inequality, meaning that no automatic data conversions are performed. Therefore, whereas the expression:

123 != "123"

evaluates to false in most situations due to automatic data type conversion, the expression evaluates to true in Navigator 4 but only in statements belonging to explicitly JavaScript 1.2 scripts. Internet Explorer 4’s equivalent of unconverted equality comparison is the nonidentity operator (!==).

Regardless of version, if you wish to compare the values of objects (for example, strings explicitly generated with the new String() constructor), you need to convert the values beforehand with methods such as toString() or valueOf().

Example

if (n != m) {
    ...
}