checking if number entered is a digit in jquery

Question

I have a simple textbox in which users enter number.
Does jQuery have a isDigit function that will allow me to show an alert box if users ente

Answer 1

String.prototype.isNumeric = function() {
    var s = this.replace(',', '.').replace(/\s+/g, '');
return s == 0 || (s/s);
}

usage

'9.1'.isNumeric() -> 1
'0xabc'.isNumeric() -> 1
'10,1'.isNumeric() -> 1
'str'.isNumeric() -> NaN