determine if function exists in IE

[yofnik]

How do you check if a function exists in IE? If I try the following:

if(document.selectSingleNode)
{
document.selectSingleNode(xpath);
}

I get an error saying the wrong number of arguements were supplied
(obviously the function exists). I have also tried

if(typeof document.selectSingleNode == "function")

but to no avail. Any advice?

Thanks.

 

[Martin Honnen]

if(typeof document.selectSingleNode == "function")

if (typeof document.selectSingleNode != 'undefined') {
// use method here e.g.
document.selectSingleNode('root/child1/child2')
}

The typeof result of that expression if document is an MSXML DOM
document is 'unknown'.
typeof document.getElementById
with IE and document being an IE HTML DOM document gives 'object' so any
comparisons alike
typeof hostObject.methodName == 'function'
might fail while doing
typeof hostObject.methodName != 'function'
should usually suffice (as long as you don't run into situations where
your code is run against two different DOM implementations where one has
a non function property named 'methodName' and the other has a function
property of that name).

 

[yofnik]

That did the trick. Thanks!