<div id="aa" class="box">
asdfghjklopmnb
</div>
<script type="text/javascript">
var mynum = document.getElementById("aa");
var mystr = mynum.innerHTML;
document.write(mystr); //asdfghjklopmnb 提取出來的字符是正確的
var mu = mystr.substring(0,6);
document.write(mu);//asdf ?但是分割之后就錯誤了,按理應該是asdfg
</script>

糾結了半天,一直找不到問題出在哪里?