Программист Максим Слепов

$('input').on('keydown', function(event){
    var x = event.keyCode;
    if ((event.keyCode > 64 && event.keyCode < 91) ||          
        (event.keyCode > 185 && event.keyCode < 193) ||
        (event.keyCode > 218 && event.keyCode < 223) ||
        (event.keyCode == 61) || (event.keyCode == 123) ||
        (event.keyCode == 173) || (event.keyCode == 59) ||
        (event.keyCode == 106) || (event.keyCode == 107) ||
        (event.keyCode == 109) ||
        (event.keyCode == 111))
    return false;
});