JavaScript，For 循环 : returned 'i' value is different from that is stored

Question

在此循环中，alert(i) 警报 12，firebug 显示 10 作为最终结果。

 for(var i=0;i<=10;i=i+2){
      document.write=i;
    }

    alert(i);

Answer 1

i每次循环迭代后都会增加。当它失败时，条件 <= 10循环中断:

0 => loop gets executed, i incremented with 2
2 => loop gets executed, i incremented with 2
4 => loop gets executed, i incremented with 2
6 => loop gets executed, i incremented with 2
8 => loop gets executed, i incremented with 2
10 => loop gets executed, i incremented with 2
12 => loop breaks => i remains at 12