Javascript Regex to limit Text Field to only Numbers (Must allow non-printable keys)

Question

I have received PHP/JS code from previous developer and I need to add number validation to a Mobile Number field. I already have the HTML validation in place but I need to

Answer 1

Try it like,

CSS

.error{border:1px solid #F00;}

SCRIPT

$('#key').on('keydown',function(e){
    var deleteKeyCode = 8;
    var backspaceKeyCode = 46;
    if ((e.which>=48 && e.which<=57) ||
         (e.which>=96 && e.which<=105)  || // for num pad numeric keys
         e.which === deleteKeyCode || // for delete key,
             e.which === backspaceKeyCode) // for backspace
         // you can add code for left,right arrow keys
    {
        $(this).removeClass('error');
        return true;
    }
    else
    {
        $(this).addClass('error');
        return false;
    }
});

Fiddle: http://jsfiddle.net/PueS2/