8.while循环及do…while

<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>