Check that variable is a number

Question

How can I check that a variable is a number, either an integer or a string digit?

In PHP I could do:

if (is_int($var)) {     echo '$var is integer'; } 

Or:

if (is_numeric($var)) {     echo '$var is numeric'; } 

How can I do it in jQuery/JavaScript?

Answer 1

The javascript function isNaN(variable) should do the trick. It returns true if the data is not a number.

Answer 2

I'd go with

isFinite(String(foo)) 

See this answer for an explanation why. If you only want to accept integer values, look here.