用JavaScript实现打地鼠游戏

源代码：

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
* {
    padding: 0;
    margin: 0;
}

.wrap {
    width: 800px;
    height: 600px;
    margin: 30px auto;
    
}

.wrap h1 {
    text-align: center;
    font-size: 40px;
}

.wrap .area {
    width: 800px;
    height: 550px;
    background-color: lightblue;
    position: relative;
}

.wrap button {
    width: 200px;
    height: 50px;
    display: block;
    font-size: 30px;
    margin: 0 auto;
}

.wrap .area img.mouse {
    width: 80px;
    height: 100px;
    position: absolute;
    left: 0;
    top: 0;
}
</style>
</head>
<body>
<div class="wrap">
    <h1>0</h1>
    <div class="area">
        <!--<img src="mouse.png" alt="" class="mouse">-->
    </div>
    <button id="btn">开始游戏</button>
</div>
<script>
var area = document.queryS