Force numeric only

gistfile1.js

jQuery.fn.ForceNumericOnly = function() {
    return this.each(function()
    {
        $(this).keydown(function(e)
        {
            var key = e.charCode || e.keyCode || 0;
            // allow backspace, tab, delete, arrows, ctrl + a, numbers and keypad numbers ONLY
            return (
                key == 8 || 
                key == 9 ||
                key == 46 ||
                (key >= 37 && key <= 40) ||
                (key >= 48 && key <= 57) ||
                (key == 65 && e.ctrlKey === true) ||
                (key >= 96 && key <= 105));
        });
    });
};