拖动滑块验证是现在的网站随处可见的，各式各样的拖动法都有。
下面实现的是某宝的拖动滑块验证：
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Document</title> <style type="text/css"> .drag{position: relative;width: 300px;height: 34px;background-color: #e8e8e8;line-height: 34px;} .bg{position: absolute;width: 40px;height: 100%;background-color: #7ac23c;} .text{position: absolute;width: 100%;margin: 0;text-align: center;} .btn{position: absolute;width: 40px;height: 32px;background: #fff url(data:image/png;base64,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) center no-repeat;border: 1px solid #ccc;cursor: pointer;} </style> </head> <body> <div class="drag"> <div class="bg"></div> <p class="text">拖动滑块验证</p> <div class="btn"></div> </div> <script> var $ = function(selector){ return document.querySelector(selector); }, box = $('.drag'),//容器 bg = $('.bg'),//绿色背景 text = $('.text'),//文字 btn = $('.btn'),//拖动按钮 done = false;//是否通过验证 btn.onmousedown = function(e){ var e = e || window.event; var posX = e.clientX - this.offsetLeft; btn.onmousemove = function(e){ var e = e || event; var x = e.clientX - posX; this.style.left = x + 'px'; bg.style.width = this.offsetLeft + 'px'; // 通过验证 if(x >= box.offsetWidth - btn.offsetWidth){ done = true; btn.onmousedown = null; btn.onmousemove = null; text.innerHTML = '通过验证'; } }; document.onmouseup = function(){ btn.onmousemove = null; btn.onmouseup = null; if(done)return; btn.style.left = 0; bg.style.width = 0; } }; text.onmousedown = function(){ return false; } </script> </body> </html>
由于是原生js实现的，因此没有加上动画效果，不然代码量太大。
代码简单，直接看下结构就明了了。