undefined in IE5

[Andrew Poulos]

I'm using code that has statements similar to this:

if (foo == undefined)

and IE 5 complains that 'undefined' is undefined. What would the
equivalent in IE 5 be? Is 'undefined' the similar enough to 'null' for
me to use 'null' instead?

Andrew Poulos

 

[Ivo]

if (foo == undefined)

Make that:

if( typeof foo === 'undefined' ) {
}

Other types are 'string', 'object' and 'function'.
See for example (watch for wrap)
<URL:
http://www.devguru.com/Technologies/ecmascript/quickref/special_operators.ht
ml#typeof >

a number returns 'number';
a string returns 'string';
the keyword true returns 'boolean';
the keyword null returns 'object';
methods, functions and predefined objects return 'function';
a variable returns the type of the data assigned to it;
a property returns the type of its value;