js，某元素在浏览器页面浮动/飘动

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .dwe{
            height: 1200px;
        }

    </style>
</head>

<body>
    <div class="dwe">_</div>
    <div class="dwe">_</div>
    <div class="dwe">_</div>
    <div class="dwe">_</div>
    <div id="Div2">
        ***** content ******
    </div>
</body>
<script>

    // JavaScript Document


    //公共脚本文件 main.js
    function addEvent(obj, evtType, func, cap) {
        cap = cap || false;
        if (obj.addEventListener) {
            obj.addEventListener(evtType, func, cap);
            return true;
        } else if (obj.attachEvent) {
            if (cap) {
                obj.setCapture();
                return true;
            } else {
                return obj.attachEvent("on" + evtType, func);
            }
        } else {
            return false;
        }
    }

    function getPageScroll() {
        var xScroll, yScroll;
        if (self.pageXOffset) {
            xScroll = self.pageXOffset;
        } else if (document.documentElement && document.documentElement.scrollLeft) {
            xScroll = document.documentElement.scrollLeft;
        } else if (document.body) {
            xScroll = document.body.scrollLeft;
        }
        if (self.pageYOffset) {
            yScroll = self.pageYOffset;
        } else if (document.documentElement && document.documentElement.scrollTop) {
            yScroll = document.documentElement.scrollTop;
        } else if (document.body) {
            yScroll = document.body.scrollTop;
        }
        arrayPageScroll = new Array(xScroll, yScroll);
        return arrayPageScroll;
    }

    function GetPageSize() {
        var xScroll, yScroll;
        if (window.innerHeight && window.scrollMaxY) {
            xScroll = document.body.scrollWidth;
            yScroll = window.innerHeight + window.scrollMaxY;
        } else if (document.body.scrollHeight > document.body.offsetHeight) {
            xScroll = document.body.scrollWidth;
            yScroll = document.body.scrollHeight;
        } else {
            xScroll = document.body.offsetWidth;
            yScroll = document.body.offsetHeight;
        }
        var windowWidth, windowHeight;
        if (self.innerHeight) {
            windowWidth = self.innerWidth;
            windowHeight = self.innerHeight;
        } else if (document.documentElement && document.documentElement.clientHeight) {
            windowWidth = document.documentElement.clientWidth;
            windowHeight = document.documentElement.clientHeight;
        } else if (document.body) {
            windowWidth = document.body.clientWidth;
            windowHeight = document.body.clientHeight;
        }
        if (yScroll < windowHeight) {
            pageHeight = windowHeight;
        } else {
            pageHeight = yScroll;
        }
        if (xScroll < windowWidth) {
            pageWidth = windowWidth;
        } else {
            pageWidth = xScroll;
        }
        arrayPageSize = new Array(pageWidth, pageHeight, windowWidth, windowHeight)
        return arrayPageSize;
    }

    //广告脚本文件 AdMove.js
    /*
    例子
    <div id="Div2">
        ***** content ******
    </div>
    var ad=new AdMove("Div2");
    ad.Run();
    */
    ////////////////////////////////////////////////////////


    var AdMoveConfig = new Object();
    AdMoveConfig.IsInitialized = false;
    AdMoveConfig.ScrollX = 0;
    AdMoveConfig.ScrollY = 0;
    AdMoveConfig.MoveWidth = 0;
    AdMoveConfig.MoveHeight = 0;
    AdMoveConfig.Resize = function () {
        var winsize = GetPageSize();
        AdMoveConfig.MoveWidth = winsize[2];
        AdMoveConfig.MoveHeight = winsize[3];
        AdMoveConfig.Scroll();
    }
    AdMoveConfig.Scroll = function () {
        var winscroll = getPageScroll();
        AdMoveConfig.ScrollX = winscroll[0];
        AdMoveConfig.ScrollY = winscroll[1];
    }
    addEvent(window, "resize", AdMoveConfig.Resize);
    addEvent(window, "scroll", AdMoveConfig.Scroll);
    function AdMove(id) {
        if (!AdMoveConfig.IsInitialized) {
            AdMoveConfig.Resize();
            AdMoveConfig.IsInitialized = true;
        }
        var obj = document.getElementById(id);
        obj.style.position = "absolute";
        var W = AdMoveConfig.MoveWidth - obj.offsetWidth;
        var H = AdMoveConfig.MoveHeight - obj.offsetHeight;
        var x = W * Math.random(), y = H * Math.random();
        var rad = (Math.random() + 1) * Math.PI / 6;
        var kx = Math.sin(rad), ky = Math.cos(rad);
        var dirx = (Math.random() < 0.5 ? 1 : -1), diry = (Math.random() < 0.5 ? 1 : -1);
        var step = 1;
        var interval;
        this.SetLocation = function (vx, vy) { x = vx; y = vy; }
        this.SetDirection = function (vx, vy) { dirx = vx; diry = vy; }
        obj.CustomMethod = function () {
            obj.style.left = (x + AdMoveConfig.ScrollX) + "px";
            obj.style.top = (y + AdMoveConfig.ScrollY) + "px";
            rad = (Math.random() + 1) * Math.PI / 6;
            W = AdMoveConfig.MoveWidth - obj.offsetWidth;
            H = AdMoveConfig.MoveHeight - obj.offsetHeight;
            x = x + step * kx * dirx;
            if (x < 0) { dirx = 1; x = 0; kx = Math.sin(rad); ky = Math.cos(rad); }
            if (x > W) { dirx = -1; x = W; kx = Math.sin(rad); ky = Math.cos(rad); }
            y = y + step * ky * diry;
            if (y < 0) { diry = 1; y = 0; kx = Math.sin(rad); ky = Math.cos(rad); }
            if (y > H) { diry = -1; y = H; kx = Math.sin(rad); ky = Math.cos(rad); }
        }
        this.Run = function () {
            var delay = 10;
            interval = setInterval(obj.CustomMethod, delay);
            obj.onmouseover = function () { clearInterval(interval); }
            obj.onmouseout = function () { interval = setInterval(obj.CustomMethod, delay); }
        }
    }


    var ad = new AdMove("Div2");
    ad.Run();


</script>

</html>
1、路在何方？路在脚下 2、何去何从？每个人都在探索，未来的方向在何处。如果说某些方向是世人已经公认的，那么就先按照公认的去走吧（ps:站在巨人的肩膀上看世界会清晰）。如果说方向，当今世人还不清晰准确。那么就大胆往前走吧，对与错并不重要。心中的方向更加重要。