machinecat520
/
zj-Exercise


			
							123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081
							<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #box1 {
            width: 100px;
            height: 100px;
            background-color: red;
            position: absolute;
        }
        #box2{
            width: 100px;
            height: 100px;
            background-color: yellow;
            position: absolute;
            left: 200px;
            top: 200px;
        }
    </style>
    <script>

        window.onload = function () {
            /**
             * 拖拽box1元素
             *  -拖拽的流程
             *      1.当鼠标在被拖拽元素上按下时，开始拖拽  onmousedown
             *      2.当鼠标移动时被拖拽元素跟随鼠标移动    onmousemove
             *      3.当鼠标松开时，被拖拽元素固定在当前位置    onmouseup
            */

            //获取box1
            var box1 = document.getElementById("box1");
            //为box1绑定一个鼠标按下事件
            box1.onmousedown = function (event) {
                event = event || window.event;
                //div的偏移量 鼠标.clientX - 元素.offsetLeft
                //div的偏移量 鼠标.clientY - 元素.offsetTop
                var ol = event.clientX - box1.offsetLeft;
                var ot = event.clientY - box1.offsetTop;

                //为document绑定一个onmousemove事件
                document.onmousemove = function (event) {
                    event = event || window.event;
                    //当鼠标移动时被拖拽元素跟随鼠标移动    onmousemove
                    //获取鼠标的坐标
                    var left = event.clientX-ol;
                    var top = event.clientY-ot;

                    //修改box1的位置
                    box1.style.left = left + "px";
                    box1.style.top = top + "px";
                };

                //为元素绑定一个鼠标松开事件
                document.onmouseup = function () {
                    //当鼠标松开时，被拖拽元素固定在当前位置    onmouseup
                    //取消document的onmousemove事件
                    document.onmousemove = null;                    
                    //取消document的onmouseup事件
                    document.onmouseup = null;
                    // alert("鼠标松开了");
                };
            };


        };

    </script>
</head>

<body>
    <div id="box1"></div>
    <div id="box2"></div>
</body>

</html>