isInt() JavaScript function
22nd of May 2006
Here's my take on a function that determines if a variable is an integer or not before or after it's been recast to an int. The functionality is very similar to Python's isdigit() function which works like this:
>>> assert "1".isdigit()
>>> assert not "1.0".isdigit()
>>> assert not "1.0".isdigit()
However, my Javascript function should return true when the input is an integer or a string of an integer. Here it goes:
function isInt(x) {
var y=parseInt(x);
if (isNaN(y)) return false;
return x==y && x.toString()==y.toString();
}
assert(isInt("1"));
assert(isInt(1));
assert(!isInt("1a"));
assert(!isInt("1.0"));
var y=parseInt(x);
if (isNaN(y)) return false;
return x==y && x.toString()==y.toString();
}
assert(isInt("1"));
assert(isInt(1));
assert(!isInt("1a"));
assert(!isInt("1.0"));
You can see it in action here. To be honest, I'm writing about this here just to not forget it the next time I need a similar function. Sorry to cause any interweb-noise.
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