to
<!DOCTYPE html>
<html>
<head>
<title>www.jobyme88.com</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<style>
li{list-style:none;background:blue;margin:2px 0;color:#ffffff}
</style>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.0.0/jquery.min.js"></script>
</head>
<body>
<ul>
<li>aaaa</li>
<li>bbbbbbbbb<br/>bbbbbb</li>
<li>cccccc<br />ccccccc<br />ccccc</li>
</ul>
<script type="text/javascript">
var maxheight = 0;
for(var i = 0;i<$("li").length;i++){
if(maxheight <= $("li").eq(i).height()){
maxheight = $("li").eq(i).height();
}
}
$("li").css('height',parseInt(maxheight)+'px');
</script>
</body>
</html>