/**
* js截取字符串，中英文都能用
* @param str:  需要截取的字符串
* @param len:  需要截取的長(zhǎng)度
*/
function subString(str, len) {
    var newLength = 0, newStr = '', singleChar;
    var chineseRegex = /[^\x00-\xff]/g;  //正則匹配
    var strLength = str.replace(chineseRegex, "**").length; //獲取字符長(zhǎng)度
    for(var i = 0; i < str.length; i++) {
        singleChar = str.charAt(i); //返回指定位置的字符
        if(singleChar.match(chineseRegex) != null) { //檢測(cè)是否為中文,是的話就算兩個(gè)字符
            newLength += 2;
        }else {
            newLength++;
        }
        //字符長(zhǎng)度大于要截取的長(zhǎng)度就跳出循環(huán)
        if(newLength > len) break;
        newStr += singleChar;
    }
    if(strLength > len) { //字符長(zhǎng)度大于要截取的長(zhǎng)度就省略
        newStr += "…";
    }
    return newStr;
}