Ignoring input characters on key down

Question

I want to ignore certain characters in my phone input, so that the database just has digits. I know I can do this easy on server side (using PHP) but I am trying to understa

Answer 1

I had to do something similar for a project I'm working on. This is how I did it.

// prevent users from typing alpha/ symbol characters on select fields
$("#modal-region").on("keydown", "#markdown, #sku", function(e) {

    var key = e.which;
    // when a keydown event occurs on the 0-9 keys the value 
    // of the "which" property is between 48 - 57 
    // therefore anything with a value greater than 57 is NOT a numeric key

    if ( key > 57) {
        e.preventDefault();

    } else if (key < 48) {

    // we don't want to disable left arrow (37), right arrow (39), delete (8) or tab (9)
    // otherwise the use cannot correct their entry or tab into the next field!

        if (key != 8 && key != 9 && key != 37 && key != 39 ) {
            e.preventDefault();
        }
    }

});