Only allow numbers in an input field

jQuery_number_only.js

$.fn.numOnly = function() {
    return this.each( function() {
        // backspace(8), dot(.), tab(0) 0-9
        var c = [8, 0, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58];
        if ($(this).attr('type') === 'text') {
            $(this).keypress( function(e) {
                if (c.indexOf(e.which, c) == -1) {
                    e.preventDefault();
                }
            });
        }
    });
};

Maybe you could do a mixture of key chars and a regexp? No idea which is more efficient (though would think regular expression route would probably be pretty quick), ( /^[0-9]+$/ || {keypresses} ) as your test?

Thanks! I updated it using a regular expression and it's a bit over 1% faster (fugit, why not!).

hahaha bloody hell! Well that's not quite the performance improvement I was expecting. Perhaps an indexOf will bump it a little more ala http://jsperf.com/exec-vs-match-vs-test-vs-search/5 but whatever, good rev!

Whaddaya know, a ~4% speed increase! :P