javascript 取得字符换长度出错

Question

<script>
var kk="AS00025";
kk=bh.substring(2,5);
kk=parseFloat(kk)+1;
alert(kk.length);
</script>
取得的alert值是undefined
是怎么回事啊，应该是2才对啊

Answer 1

<script>
var bh="AS00025";
var kk;
kk=bh.substring(2,5);
kk=parseFloat(kk)+1;
alert(kk.length);
</script>

Answer 2

number 没有 length 属性，要先 toString() 才行！L@_@K
var kk="AS00025";
kk=kk.substring(2,7);
kk=parseInt(kk,10)+1;
document.write(typeof(kk),"<br />"); // number
document.write(kk,"<br />"); // 26
document.write(kk.toString().length,"<br />"); //2

Answer 3

alert(kk.length);
改成
alert((''+kk+'').length);

Answer 4

parseFloat(kk)已经转化为Number类型了。所以kk没有length属性。