<html> <head> <meta charset="UTF-8"> <title>Document</title> <style> *{ margin: 0; padding: 0; } .scroll{ margin:100px; width: 500px; height: 5px; background: #ccc; position: relative; } .bar{ width: 10px; height: 20px; background: #369; position: absolute; top: -7px; left: 0; cursor: pointer; } .mask{ position: absolute; left: 0; top: 0; background: #369; width: 0; height: 5px; } </style> </head> <body> <div> <div> </div> <div></div> </div> <p></p> <script> var scroll = document.getElementById('scroll'); var bar = document.getElementById('bar'); var mask = document.getElementById('mask'); var ptxt = document.getElementsByTagName('p')[0]; var barleft = 0; bar.onmousedown = function(event){ var event = event || window.event; var leftVal = event.clientX - this.offsetLeft; var that = this; // 拖动一定写到 down 里面才可以 document.onmousemove = function(event){ var event = event || window.event; barleft = event.clientX - leftVal; if(barleft < 0) barleft = 0; else if(barleft > scroll.offsetWidth - bar.offsetWidth) barleft = scroll.offsetWidth - bar.offsetWidth; mask.style.width = barleft +'px' ; that.style.left = barleft + "px"; ptxt.innerHTML = "已经走了" + parseInt(barleft/(scroll.offsetWidth-bar.offsetWidth) * 100) + "%"; //防止选择内容--当拖动鼠标过快时候，弹起鼠标，bar也会移动，修复bug window.getSelection ? window.getSelection().removeAllRanges() : document.selection.empty(); } } document.onmouseup = function(){ document.onmousemove = null; //弹起鼠标不做任何操作 } </script> </body> </html>
效果图：
