Merge branch 'release/5.7' into gray

@@ -4,14 +4,14 @@
  * @Last Modified by: Targaryen
  * @Last Modified time: 2017-05-22 16:53:18
  */
-let stringHandle = {
+var stringHandle = {
 
     /**
      * 汉字相当于两个字符的字符串长度计算
      * @param {*} str
      */
     chinese2(str) {
-        let total = 0,
+        var total = 0,
             charCode,
             i,
             len;
@@ -33,15 +33,15 @@ let stringHandle = {
      * @param {*} n
      */
     sub_chinese2(str, n) {
-        let r = /[\u4E00-\u9FA5]/g;
+        var r = /[\u4E00-\u9FA5]/g;
+        var m = Math.floor(n / 2);
+        var i;
 
         if (str.replace(r, 'mm').length <= n) {
             return str;
         }
 
-        let m = Math.floor(n / 2);
-
-        for (let i = m; i < str.length; i++) {
+        for (i = m; i < str.length; i++) {
             if (str.substr(0, i).replace(r, 'mm').length >= n) {
                 return str.substr(0, i);
             }