Is it possible to determine if function has arguments? [duplicate]

Question

Is it posible to know, if my function takes vars?

For example:

function ada (v) {};
function dad () {};
alert(ada.hasArguments()); // true
alert(dad.hasArguments()); // false

Answer 1

Yes. The length property of a function returns the number of declared arguments:

alert(ada.length); // 1
alert(dad.length); // 0

Answer 2

The function's length property represents the number of formal parameters. Note that this is not necessarily equal to the number of actual parameters:

function foo(one, two, three) {
    return foo.length === arguments.length;
}

foo("test");
foo("test", "test", "test");

Output:

false
true