<!DOCTYPE html>
<html en">
<head>
<meta charset="UTF-8">
<title>循環輸出helloworld</title>
<script type="text/javascript">
document.write('使用JS循環列印helloworld')
for(var i=0;i<5;i++){
document.write('<h3>helloworld</h3>')
}
document.write('<h1>helloworld</h1>')
</script>
</head>
<body>
文檔主體内容
</body>
</html> 
循環輸出helloworld ![主流浏覽器四大綜合性能測試[圖]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=)