<script type="text/javascript">
var array = ["1","2","3","4"];
alert(aray.indexOf(String(2)));
alert(array.indexOf(5));
</script>
<script type="text/javascript">
var array = [1,2,3,4];
alert(array.indexOf(2));
alert(array.indexOf(5));
</script>
如果變量在數組内,則傳回1,反之,則傳回-1;
尤其要注意判斷變量的類型,如果值相等,類型不同的話,也會傳回-1;