超过长度的字符截取指定长度，超出部分以...显示

$(function () {
        subString('abcdef你好！Hello World', 6);
    })
    //超过长度的字符截取指定长度，超出部分以...显示，中文字符是两个字符长度
    function subString(str, len) {
        var newLength = 0;
        var newStr = "";
        var chineseRegex = /[^x00-xff]/g;//中文正则表达式
        var singleChar = "";
        var strLength = str.replace(chineseRegex, "**").length;
        if (strLength > len) {
            for (var i = 0; i < strLength; i++) {
                singleChar = str.charAt(i).toString();
                if (singleChar.match(chineseRegex) != null) {
                    newLength += 2;
                }
                else {
                    newLength++;
                }
                if (newLength > len) {
                    break;
                }
                newStr += singleChar;
            }

            if (strLength > len) {
                newStr += "...";
            }
        } else {
            newStr = str;
        }
        return newStr;
    }