<head>
<style>
a { color: green; }
</style>
</head>
<body>
<script>
function toggle(id)
{
var node = document.getElementById(id);
node.style.display == 'none' ? node.style.display = 'block' : node.style.display = 'none';
}
</script>
<div style="border:2px solid red"><a onclick="toggle('first');">First</a><span id="first" style="display:none">
First Content.
</span><a onclick="toggle('second');">Second</a><span id="second" style="display:none">
Second Content.
</span><a onclick="toggle('third');">Third</a><span id="third" style="display:none">
Third Content.<a onclick="toggle('crashme');"> Crash Me</a><span id="crashme" style="display:none">
You win!
</span></div>