javascript滚轮控制模拟滚动条

2020-11-27 来源：乌哈旅游

此实例通过对滚轮事件的监听，通过滚轮控制滚动条的上下移动，可以将其修改后运用与使用滚轮缩放图片、改变透明度等特效。

<!DOCTYPE html> 
<html> 
 <head> 
 <meta charset="UTF-8"> 
 <title></title> 
 <style type="text/css"> 
 *{ 
 margin: 0; 
 padding: 0; 
 } 
 #boxwrap{ 
 position: relative; 
 width: 15px; 
 height: 500px; 
 margin: 50px auto; 
 box-sizing: border-box; 
 border: 1px solid gainsboro; 
 border-radius: 6px; 
 } 
 #box{ 
 position: absolute; 
 left: 0px; 
 top: 0px; 
 width: 13px; 
 height: 30px; 
 background: gray; 
 border-radius: 6px; 
 } 
 </style> 
 <script type="text/javascript"> 
 window.onload = function (){ 
 var boxwrp = document.getElementById('boxwrap'); 
 var box = document.getElementById('box'); 
 //兼容firefox 
 if(boxwrp.addEventListener){ 
 document.addEventListener("DOMMouseScroll", fn, false); 
 } 
 document.onmousewheel = fn;//兼容IE、chrome 
 
 function fn(ev){ 
 var ev = ev||event; 
 var bool = false; 
 //IE、chrome 向上：120，向下：-120 
 if(ev.wheelDelta){ 
 bool= ev.wheelDelta > 0? true : false; 
 } 
 //firefox 向上：-3，向下：3 
 else{ 
 bool= ev.detail < 0? true : false; 
 } 
 
 if(bool){ 
 if(box.offsetTop>=10){ 
 box.style.top = box.offsetTop - 10 + "px"; 
 } 
 else{ 
 box.style.top = 0; 
 } 
 
 } 
 else{ 
 if(box.offsetTop<=boxwrp.offsetHeight-box.offsetHeight-10){ 
 box.style.top = box.offsetTop + 10 + "px"; 
 } 
 else{ 
 box.style.top = boxwrp.offsetHeight - box.offsetHeight + "px"; 
 } 
 } 
 } 
 } 
 </script> 
 </head> 
 <body> 
 <div id="boxwrap"> 
 <div id="box"></div> 
 </div> 
 </body> 
</html>

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javascript滚轮控制模拟滚动条