只允许输入数字

 function OnlyNum() {
    if (!(event.keyCode == 46) && !(event.keyCode == 8) && !(event.keyCode == 37) && !(event.keyCode == 39)) {
        if (!((event.keyCode >= 48 && event.keyCode <= 57) || (event.keyCode >= 96 && event.keyCode <= 105) || (event.keyCode == 109) || (event.keyCode == 189))) {
            event.returnValue = false;
        }
    }
}