数组合并法（IE7性能优化）

 1 var str = "I'm a thirty-five character string.",

 2     strs = [],

 3     newStr,

 4     appends = 5000;

 5 

 6 while (appends--) {

 7     strs[strs.length] = str;

 8 }

 9 

10 newStr = strs.join("");

以上代码为了让IE7或者更低版本的浏览器性能更优。其他浏览器使用以下代码：

1 var str = "I'm a thirty-five character string.",

2     newStr = "",

3     appends = 5000;

4 

5 while (appends--) {

6     newStr += str;

7 }