This is what I was looking for:
$('input[type=number]').keypress(function(e) {
if (!String.fromCharCode(e.keyCode).match(/[0-9\.]/)) {
return false;
}
});
I understand preventing user input can be annoying and this still allows invalid input such as 1.2.3
However in this situation it is exactly what I needed. Hopefully it will be of use to someone else. Thanks to @int32_t for the suggestion.