????：<!DOCTYPE html><html><head> <title></title> <script type="text/javascript" src="jquery-3.3.1.js"></script></head><body>
<!DOCTYPE html>
<html>
<head>
<title></title>
<script type="text/javascript" src="jquery-3.3.1.js"></script>
</head>
<body>
<script type="text/javascript">
//jquery就緒
//$(選擇器).action()
$(document).ready(function(){
// $str="wo是一個聲明變量"
// alert($str);
$("div").hide()
$("button").click(function(){
$("div").show()
})
})
</script>
<div style="width:100px;height:100px;background:pink;"></div>
<button>點擊</button>
</body>
</html>