求一个js的代码用于输出换行
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link href="<{$res}>/css/layout.css" rel="stylesheet" type="text/css" />
<div id="container">
<div id="main">
<div class="leftb">
<div class="leftbox1">
<{section loop=$data name="la"}>
<div class="left1">
<a href="#" title="#"><img src='<{$public}>/images/<{$data[la].pic}>'></a>
<br><a href="#" title="#"><{$data[la].service_name}></a>
</div>
<{/section}>
</div>
</div>
</div>
</div>
</html>
求大神帮忙写个程序,小弟从section那里传递进来一个数组,但是在页面设置时想规定只能每一行输出4张图片,接着就换行,求教大神们这个用js应该怎么写,谢啦