コードを古いバージョンのブラウザー (IE8 など) で動作させたい場合。jqueryを使用します。
http://www.mkyong.com/jquery/jquery-toggle-example-to-display-and-hide-content/
例:
<html>
<head>
<title>jQuery toggle to display and hide content</title>
<script type="text/javascript" src="http://code.jquery.com/jquery-1.7.2.js"></script>
<script>
$(document).ready(function() {
$('.nav-toggle').click(function(){
//get collapse content selector
var collapse_content_selector = $(this).attr('href');
//make the collapse content to be shown or hide
var toggle_switch = $(this);
$(collapse_content_selector).toggle(function(){
if($(this).css('display')=='none'){
//change the button label to be 'Show'
toggle_switch.html('Show');
}else{
//change the button label to be 'Hide'
toggle_switch.html('Hide');
}
});
});
});
</script>
<style>
.round-border {
border: 1px solid #eee;
border: 1px solid rgba(0, 0, 0, 0.05);
-webkit-border-radius: 4px;
-moz-border-radius: 4px;
border-radius: 4px;
padding: 10px;
margin-bottom: 5px;
}
</style>
</head>
<body>
<section class="round-border">
<h2>jQuery toggle() to hide/show collapse content</h2>
<div>
<button href="#collapse1" class="nav-toggle">Show</button>
</div>
<div id="collapse1" style="display:none">
<p>Bla bla bla bla</p>
</div>
</section>
</body>
</html>