Check if string contains only digits

Question

Hello

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 wanna make sure the input contains ONLY digits and no other letters. 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

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

Answer 2

Well, you can use the following regex:

^\d+$

Answer 3

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

Answer 4

var isNumber =  /^\d+$/.test(theValue);

Answer 5

String.prototype.isNumber = function(){return /^\d+$/.test(this);}
console.log("123123".isNumber()); // outputs true
console.log("+12".isNumber()); // outputs false