Check if string contains only digits

Question

I want to check if a string contains only digits. I used this:

var isANumber = isNaN(theValue) === false;  if (isANumber){     .. } 

But realized that it also allows + and -. Basically, I want to make sure an input contains ONLY digits and no other characters. Since +100 and -5 are both numbers, isNaN() is not the right way to go. Perhaps a regexp is what I need? Any tips?

Answer 1

how about

let isnum = /^\d+$/.test(val); 

Answer 2

string.match(/^[0-9]+$/) != null;