Check if function expect any data

Question

It is possible to check if function expect/need any data?

function one(){

}
function two(ineedvar){

}

So i have to functions and I would like to check which of them need var between ().

No, you can't do it *reliably*. But wanting to do this *usually* is a sign of flawed design. What do you need it for? — Ingo Bürk, Sep 05 '13 at 17:52
Don't forget - a function doesn't have to define any parameters to accept them - it can access the `arguments` object — Ian, Sep 05 '13 at 18:00

PSL · Accepted Answer · 2013-09-05T18:00:51.603

6

You can use .length property of the function to see if it takes any argument.

i.e two.length

But note that function can also take arguments without having it define it in the function declaration, so can't rely on that always.

edited Sep 05 '13 at 18:00

answered Sep 05 '13 at 17:52

PSL

score 2 · Answer 2 · answered Sep 05 '13 at 17:53

2

Use length property of the Function object:

one.length /* 0 */
two.length /* 1 */

answered Sep 05 '13 at 17:53

Denys Popov

2 Answers2