简单的为按钮添加点击事件
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<button id="btn">点击</button>
<div id="demo" style="display: none;">这是一个惊喜!</div>
<script>
function show() {
let oBtn = document.getElementById("btn");
let oDemo = document.getElementById("demo");
oBtn.onclick = function() {
oDemo.style.display = 'block';
}
}
show('btn', 'demo');
</script>
</body>
</html>