function hide(div) {
if (document.getElementById)
document.poppedLayer = eval('document.getElementById(div)');
else if (document.all)
document.poppedLayer = eval('document.all[div]');
else
document.poppedLayer = eval('document.layers[div]');
document.poppedLayer.style.display = "none";
}
function show(div) {
if (document.getElementById)
document.poppedLayer = eval('document.getElementById(div)');
else if (document.all)
document.poppedLayer = eval('document.all[div]');
else
document.poppedLayer = eval('document.layers[div]');
document.poppedLayer.style.display = "block";
}
#MyDiv {
display: none;
}
<a href="javascript:show('MyDiv');">Show
</a>
<a href="javascript:hide('MyDiv');">Hide
</a>
<div id="MyDiv"></div>