JavaScript, check if value is integer?

[HAL9000]

Hey guys,

In JS how do you check if a value is an integer? (whole number)

 

[iCyborg]

You can write your own function that does that. E.g. there's a builtin typeof that distiguishes numbers from strings, but not integers from floats. You could use that and further check that value.toString doesn't have '.' inside or some such...

Or rip it off from internet, I'm sure it can be found if you google.

 

[PhatoseAlpha]

function isInteger(value)
{
if (typeof(value)) == "number")
{
return (floor(value)==value);
}
else
{return false;}
}

 

[Snapster]

function isInteger(value)
{
if (typeof(value)) == "number")
{
return (floor(value)==value);
}
else
{return false;}
}

Could be simplified as:

function isInteger(value) {
return (!isNaN(value) && Math.floor(value) === value);
}

Keeping in mind that this is a strict comparison will return true for say 1,2,3,4 but not when it's in string form "1", "2", "3", "4" which form values often are.

If you want to take string equivalents you might need something like:

function isInteger(value) {
return (!isNaN(value) && Math.floor(value) === parseInt(value));
}