8.while循环及do…while
<![CDATA[
<script type="text/javascript">
var arr=[1,2,3,4,5,6,7,8,9];
var alen =arr.length;
var i=0;
while (i<alen){
document.write(arr[i]+'<br>');<!--结果输出在页面中document为文档节点-->
i++;
}
document.write('<hr>');
//var arr=[1,2,3,4,5,6,7,8,9];
i=0;
do{
document.write(arr[i]+'<br>');<!--结果输出在页面中document为文档节点-->
i++;
}while (i<alen);
</script>
]]>