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

We'll respond to both keypresses, and the blur event. When somebody press a key, we check to see if the key entered is a number. If it is, we permit it. Otherwise, we prevent it.

If the field is blurred, we remove any non-numerical values, and all those values that follow. This will prevent the user from pasting in non-numerical strings:

$("#textfield").on("keypress blur", function(e){
    if ( e.type === "keypress" )
        return !!String.fromCharCode(e.which).match(/^\d$/);
    this.value = this.value.replace(/[^\d].+/, "");
});

Demo: http://jsfiddle.net/jonathansampson/S7VhV/5/