Javascript check for decimal place (check if value is an integer)

Question

Hi,

i am looking for an easy way in javascript to check if a number has a decimal place in it (is an integer) ...

23 -> OK
5 -> OK
3.5 -> not OK
34.345 -> not OK

if(number is integer) {...}

thx alot.

Answer 1

Using modulus will work:

num % 1 != 0
// 23.5 % 1 = 0.5

Answer 2

The most common solution is to strip the integer portion of the number and compare it to zero like so:

function Test()
{
     var startVal = 123.456
     alert( (startVal - Math.floor(startVal)) != 0 )
}

Answer 3

var re=/^-?[0-9]+$/;
var num=10;
re.test(num);

Answer 4

//How about byte-ing it?

Number.prototype.isInt= function(){
 return this== this>> 0;
}

I always feel kind of bad for bit operators in javascript-

they hardly get any exercise.