【案例】鼠标按下,DIV跟随移动

<!DOCTYPE html>

<html lang="en">

<head>

        <meta charset="UTF-8">

        <title>鼠标按下,DIV跟随移动</title>

        <style>

                 *{

                         margin: 0;

                         padding: 0;

                 }

                 #ball{

                         200px;

                         height: 200px;

                         background: pink;

                         border-radius: 50%;

                         cursor: move;

                         position: absolute;

                 }

        </style>

</head>

<body>

        <div id="ball"></div>

</body>

<script>

        //获取元素

        var ball = document.getElementById('ball');

        console.log(ball);

        //声明全局变量

        var leftCha,topCha;

        //定义鼠标是否按下的标识

        var isDown = false;

        ball.onmousedown = function(e){

                 var e = e || window.event;

                 leftCha = e.clientX - ball.offsetLeft;

                 topCha = e.clientY - ball.offsetTop;

                 isDown = true;

        }

        window.onmousemove = function(e){

                 var e = e || window.event;

                 if(!isDown){

                         return;  //终止程序执行

                 }

                 ball.style.left = e.clientX - leftCha + 'px';

                 ball.style.top = e.clientY - topCha + 'px';

        }

        ball.onmouseup = function(e){

                 isDown = false;

        }

</script>

</html>

原文地址:https://www.cnblogs.com/sherryStudy/p/onmousedown.html