JS仿贪吃蛇：一串跟着鼠标的Div

贪吃蛇是一款80后、90后比较熟悉的经典游戏，下面通过简单的JS代码来实现低仿版贪吃蛇效果：随着鼠标的移动，在页面中呈现所有Div块跟随鼠标依次移动，效果如下图所示。

<!DOCTYPE html>
<html lang="zh-CN">

<head>
    <meta charset="UTF-8">
    <title>习题-仿select下拉框</title>
    <style>
        div {
            width: 20px;height: 20px;background-color: purple;position: absolute;
        }
    </style>
    <script>
        //此处写代码
    </script>
</head>
<body>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
</body>

</html>

　　参考代码：

 window.onload = function () {
    // getPos函数获取鼠标的坐标
    function getPos(ev) {
        var scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
        var scrollLeft = document.documentElement.scrollLeft || document.body.scrollLeft;
        return { x: ev.clientX + scrollTop, y: ev.clientY + scrollLeft };
    }
    document.onmousemove = function (ev) {
        var oEvent = ev || event;
        var pos = getPos(oEvent);
        var aDiv = document.getElementsByTagName('div');
        //递减循环
        for (var i = aDiv.length - 1; i > 0; i--) {
            aDiv[i].style.left = aDiv[i - 1].offsetLeft + 'px';
            aDiv[i].style.top = aDiv[i - 1].offsetTop + 'px';
        }
        aDiv[0].style.left = pos.x + 'px';
        aDiv[0].style.top = pos.y + 'px';
    }
}

　　

思考：为什么采用下面递增循环代码就无法达到预期效果？

代码：

// 与参考文档区别部分
for (var i = 0; i < aDiv.length - 1; i++) {
    aDiv[i + 1].style.left = aDiv[i].offsetLeft + 'px';
    aDiv[i + 1].style.top = aDiv[i].offsetTop + 'px';
}

　　效果：

如果递增循环设计进行修改后，可以实现其它独特效果：(平移连珠直线)

代码：

window.onload = function () {
    // getPos函数获取鼠标移动时的坐标
    function getPos(ev) {
        var scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
        var scrollLeft = document.documentElement.scrollLeft || document.body.scrollLeft;
        return { x: ev.clientX + scrollTop, y: ev.clientY + scrollLeft };
    }
    document.onmousemove = function (ev) {
        var oEvent = ev || event;
        var pos = getPos(oEvent);
        var aDiv = document.getElementsByTagName('div');
        for (var i = 0; i < aDiv.length - 1; i++) {
            aDiv[i + 1].style.left = aDiv[i].offsetLeft + 20 + 'px';
            aDiv[i + 1].style.top = aDiv[i].offsetTop + 20 + 'px';
        }
        aDiv[0].style.left = pos.x + 'px';
        aDiv[0].style.top = pos.y + 'px';
    }
}
posted @ 2019-07-03 16:13  请叫我二狗哥  阅读(481)  评论(0)    收藏  举报