Which is the proper way of filtering numeric values for a text field?

Question

I\'m working on a textfield working with the kind of validation that wouldn\'t let you enter other than numeric values. As so, my initial code looked quite simple and simila

Answer 1

this will allow both int. it also removes text if user copy and paste with mouse.

$(document).ready(function () {
    $('#textfield').bind('keyup blur', function (e) {
        if (e.type == 'keyup') {
            if (parseInt($(this).val()) != $(this).val()) {
                $(this).val($(this).val().slice(0, $(this).val().length - 1));
            }
        } else if (e.type == 'blur') {
            $(this).val('');
        }
    });
});