Question

Say you have two functions with the following signatures:

1. addClass( class )
2. addClass( class, duration )

These live in a third party library _{^{(no prizes for guessing which!!)}}.

If you call addClass() with two parameters but only have signature 1 registered, there will be no error and signature 1 will be called. The second parameter is ignored.

So is there a way to detect that signature 2 with two parameters has been registered?

Answer 1

You can use the length property of the function object to check the signature. Example:

function x(a) {}
function y(a,b) {}

alert(x.length); // shows "1"
alert(y.length); // shows "2"