JavaScript number only lock

function(event) {
    // Allow: backspace, delete, tab, escape, and enter
    if ( event.keyCode == 46 || 
         event.keyCode == 8 || 
         event.keyCode == 9 ||
         event.keyCode == 27 || 
         event.keyCode == 13 || 
         // Allow: Ctrl+A
        (event.keyCode == 65 && event.ctrlKey === true) || 
         // Allow: home, end, left, right
        (event.keyCode >= 35 && event.keyCode <= 39)) {
             // let it happen, don't do anything
             return;
    }
    else {
        // Ensure that it is a number and stop the keypress
        if (event.shiftKey || (event.keyCode < 48 || event.keyCode > 57) && 
            (event.keyCode < 96 || event.keyCode > 105 )) {
            event.preventDefault(); 
        }   
    }
}