werty1001,
Вариант для современных браузеров
<!DOCTYPE HTML>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
[data-div].show{
display: block;
}
[data-div] {
display: none;
}
div{
cursor: pointer;
display: inline-block;
}
</style>
<script>
document.addEventListener("click", function(event) {
var el = event.target,
show = el.dataset.show,
close = el.dataset.close;
el = show || close;
if (el) {
document.querySelector("[data-div='"+ el +"']").classList[show ? "add" : "remove"]("show");
}
});
</script>
</head>
<body>
<div data-show="Menu">Show</div>
<div data-close="Menu">Close</div>
<div data-div="Menu">Memu</div>
</body>
</html>