javascript--》实现数字的千分号添加

实现数字的千分号添加

类似：

123456789=>123,456,789

function percent(str, step, splitor) {
        str = str.toString();
        var len = str.length;
        if(len > step) {
            var l1 = len%step, 
                l2 = parseInt(len/step),
                arr = [],
                first = str.substr(0, l1);
            if(first != '') {
                arr.push(first);
            };
            for(var i=0; i<l2 ; i++) {
                arr.push(str.substr(l1 + i*step, step));									 
            };
            str = arr.join(splitor);
        };
        return str;
}