js 拖拽 鼠标事件，放大镜效果

时间：2022-04-15 19:17:28

设置网站播放视频 只有一个是播放的

//需要引入jquery  
 var v = $("video")

    v.bind("play",function(){

        for(var i =0; i<v.length; i++){

            (i == v.index(this))?v[i].play():v[i].pause();

        }

    })

设置 网站固定 导航条或者是搜索框

var box1 = document.getElementsByClassName("box1")[0];

        var box2 = document.getElementsByClassName("box2")[0];

        var box3 = document.getElementsByClassName("box3")[0];

        var sTop

        document.onscroll = function(){

            sTop = window.pageYOffset || document.body.scrollTop || document.documentElement.scrollTop;

            // sTop >= 200?box2.classList.add("fix"):box2.classList.remove("fix"); // 实用类名

            sTop >= box1.scrollHeight?box2.style.cssText="position:fixed;top:0;":box2.style.cssText="position:static;";

        }

图片随屏幕滚动而跟着走

 var topHeight

        window.onscroll=function(){

            topHeight= window.pageYOffset;

            box[0].style.top = topHeight+ 100 +"px"

            box[1].style.top = topHeight+ 100 +"px"

        }
// 还需要给元素加一个过渡CSS3属性 transition：time;

最后一个实例 可以拖动的放大镜

<!DOCTYPE html>

<html>

<head>

    <title>放大镜</title>

    <link href='http://fonts.googleapis.com/css?family=Ubuntu' rel='stylesheet' type='text/css'>

    <style type="text/css">

        html,body,head,h1 {

            margin: 0;

            padding: 0;

        }

        .container {

            width: 622px;

           margin: 20px;

           height: 346px;

           border: solid 1px #ccc;

        }

        .container h1 {

            text-align: center;

            background-color: rgba(0,0,0,.3);

            cursor: pointer;

        }

        .smallBox {

            width: 300px;

            border-right: solid 1px #ccc;

            margin-right: 20px;

            position: relative;

            float: left;

        }

        .shade {

            position: absolute;

            width: 100px;

            height: 100px;

            top: 0;

            left: 0;

            background: url(images/2.png);

            display: none;

            cursor: move;

        }

        .bigBox {

            float: left;

            width: 300px;

            height: 300px;

            overflow: hidden;

            display: none;

        }

    </style>

</head>

<body>

    <div class="container">

        <div class="title">

            <h1>放大镜</h1>

        </div>

        <div class="smallBox">

            <img width="300" src="data:images/1.jpg" alt="">

            <span class="shade"></span>

        </div>

        <div class="bigBox">

            <img src="data:images/1.jpg" alt="">

        </div>

    </div>

    <script type="text/javascript">

        // 获取相关元素

        var smallBox = document.getElementsByClassName("smallBox")[0];

        var shade = document.getElementsByClassName("shade")[0];

        var bigBox = document.getElementsByClassName("bigBox")[0];

        var bigImg = bigBox.getElementsByTagName("img")[0];

        var title = document.getElementsByTagName("h1")[0];

        var content = document.getElementsByClassName("container")[0];

        // console.log(content);

        // 给标题添加一个拖拽效果

        title.onmousedown = function(e){

            e = e || window.event;

            var x = e.offsetX;

            var y = e.offsetY;

            document.onmousemove = function(e){

                e = e || window.event;

                // 禁止文字被选中

                window.getSelection?window.getSelection().removeAllRanges():document.selection.empty();

                content.style.marginLeft = e.clientX -x+ "px";

                content.style.marginTop = e.clientY -y+ "px";

            }

        }

        // 取消事件 必须添加两个事件取消 如果只添加前面一个会有bug

        title.onmouseup = function(){

            document.onmousemove = null;

        }

        title.onmouseout = function(){

            document.onmousemove = null;

        }

        // 给图片添加一个放大镜效果

        smallBox.onmouseenter = function(){

            shade.style.display = "block";

            bigBox.style.display = "block";

            smallBox.onmousemove = function(e){

                e = e || window.event;

                // 移动的距离 = 屏幕可视区域的距离+屏幕被卷去的距离(如果在屏幕没有滚动条的时候也可以不用减去)-鼠标在盒子内的距离-图片上的遮罩矩形的长宽一半(目的是让鼠标在遮罩的正中心)

                var shadeX = e.clientX + window.pageXOffset-smallBox.offsetLeft-shade.offsetWidth/2;

                var shadeY = e.clientY + window.pageYOffset-smallBox.offsetTop-shade.offsetHeight/2;

                if(shadeX < 0) shadeX = 0;

                if(shadeX >= smallBox.offsetWidth - shade.offsetWidth) shadeX = smallBox.offsetWidth - shade.offsetWidth-1;

                if(shadeY < 0) shadeY = 0;

                if(shadeY >= smallBox.offsetHeight - shade.offsetHeight) shadeY = smallBox.offsetHeight - shade.offsetHeight-1;

                shade.style.left = shadeX + "px";

                shade.style.top = shadeY + "px";

                // 300-100 = 200 : 800-300 = 500 ==> 也就是2.5倍

                // 我用的是通过改变margin的值来移动元素 也可以通过定位移动元素

                bigImg.style.marginLeft = -shadeX*2.5 +"px"

                bigImg.style.marginTop = -shadeY*2.5 + "px";

            }

        }

        smallBox.onmouseleave = function(){

            shade.style.display = "none";

            bigBox.style.display = "none";

        }

    </script>

</body>

</html>

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