js补零方法

function getZero(num, index) {
    if((parseInt(num) != 0) && (typeof num == "undefind" || num == null || num == "" || isNaN(num))) return num;
        var _num = parseInt(num);
        if(!index)  index = 2;
        if(_num != 0) {
            if(_num<0){
                _num = -_num;
                for (var i = 1; i < parseInt(index); i++) {
                    if(parseInt(_num) < Math.pow(10,i)) {
                        _num = "0" + _num;
                    }
                }
                _num = "-"+_num;
                return _num;
            }
            for (var i = 1; i < parseInt(index); i++) {
                if(parseInt(_num) < Math.pow(10,i)) {
                    _num = "0" + _num;
                }
            }
        }
    return _num;
}