<script type="text/javascript">
var arr=['*','##',"***","&&","****","##*"];
arr[7]= "**";
document.write(arr.length);
alert("数组arr的长度为: " + arr.length);
var n = [0,7,2,4];
for(i in n){document.write("<br>"+arr[n[i]]);};
for(i in n){document.write("<br>"+arr[n[n.length-i-1]]);};
</script>试试这个^___^
