Code
<a href='javascript: toggle()'>toggle</a>
<div id='div1' style='display:none'>
Don't display me
</div>
<script>
function toggle(){
var div1 = document.getElementById('div1')
if (div1.style.display == 'none') {
div1.style.display = 'block'
} else {
div1.style.display = 'none'
}
}
</script>