Comment

Aadit M Shah July 24, 2011

The simplest form of isInt is as follows (for a number n):

parseInt(n) === n; //isInt

That's it - you don't need a function call! Similarly, we have the following:

parseInt(n) !== n; //isNotInt
parseFloat(n) === n; //isFloat
parseFloat(n) !== n; //isNotFloat

Replies

Anonymous November 3, 2011

And how would you check this "03" ?

Bobinours June 13, 2012

It depend of the version of EcmaScript and the browser.

"If the input string begins with "0", radix is eight (octal). This feature is non-standard, and some implementations deliberately do not support it (instead using the radix 10)."

"The ECMAScript 5 specification of the function parseInt no longer allows implementations to treat Strings beginning with a 0 character as octal values."

(Source : https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/parseInt )

So... For this reason, you should always specify a radix when using parseInt().

parseInt("03", 10);

Anonymous October 15, 2012

Why this:

var n = 3.0;
alert(parseInt(n)===n);

alerts "true"?

Peter Bengtsson October 15, 2012

Python does the same:

>>> 3.0 == 3
True

But in python you can do:

>>> 3 is 3
True
>>> 3.0 is 3.0
True
>>> 3.0 is 3
False