<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
</head>
<body>
<div id="control" onclick="f()">-</div>
<ul id="list">…</ul>
<script>
var ul = document.querySelector('#list');
var ctrl = document.querySelector('#control');
function f(){
ul.style.display = ul.style.display === 'none'?'block':'none';
ctrl.innerHTML = ctrl.innerHTML === '-'?'+':'-';
}
</script>
</body>
</html>