Question

function Add(a, b) {      }

If we call a javascript function like – onclick="Add(1)"

Why do we don’t get error even though we pass only a single parameter or even more than 2 parameters (in case of above example) to function ?
How Java script treats above scenario?

Answer 1

Javascript is a dynamic, weakly-typed language. As a result, it doesn’t strictly enforce method signatures.

Add is a Function object. It has a property called arguments which is an array-like object that contains the parameters that you pass in. As a convenience, it will also create local variables called a and b and assign the first and second elements in arguments to them. In the case where you only have one input parameter, b will be undefined.

So, Javascript will treat

 Add(1)

and

 Add(1, undefined)

as almost identical. The difference here is that the arguments variable will be of length 2 instead of 1. From a purely pragmatic standpoint, though, they’re pretty well the same.