基于JavaScript实现自定义滚动条

时间：2021-05-25

可直接使用的js滚动条，先看看效果图：

代码如下

<!DOCTYPE html><html lang="en"><head> <meta charset="UTF-8"> <title>自定义滚动条</title></head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><title>滚动条</title><style type="text/css">*{ margin:0; padding:0;}#mainBox{ width:400px; height:500px; border:1px #bbb solid; position:relative; overflow:hidden; margin:50px auto; }#content{ height:2500px; position:absolute; left:0; top:0; background:url(https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1485320653275&di=b7bc29cc2c7b3388d44958d8f97db0a3&imgtype=0&src=http%3A%2F%2Fphotocdn.sohu.com%2F20151212%2Fmp48094209_1449905365456_7.jpg) }.scrollDiv{ width:18px; position:absolute; top:0; background:#666; border-radius:10px;}</style></head><body><div id="mainBox"> <div id="content"></div></div><script type="text/javascript">var doc=document;var _wheelData=-1;var mainBox=doc.getElementById('mainBox');function bind(obj,type,handler){ var node=typeof obj=="string"?$(obj):obj; if(node.addEventListener){ node.addEventListener(type,handler,false); }else if(node.attachEvent){ node.attachEvent('on'+type,handler); }else{ node['on'+type]=handler; }}function mouseWheel(obj,handler){ var node=typeof obj=="string"?$(obj):obj; bind(node,'mousewheel',function(event){ var data=-getWheelData(event); handler(data); if(document.all){ window.event.returnValue=false; }else{ event.preventDefault(); } }); //火狐 bind(node,'DOMMouseScroll',function(event){ var data=getWheelData(event); handler(data); event.preventDefault(); }); function getWheelData(event){ var e=event||window.event; return e.wheelDelta?e.wheelDelta:e.detail*40; }}function addScroll(){ this.init.apply(this,arguments);}addScroll.prototype={ init:function(mainBox,contentBox,className){ var mainBox=doc.getElementById(mainBox); var contentBox=doc.getElementById(contentBox); var scrollDiv=this._createScroll(mainBox,className); this._resizeScorll(scrollDiv,mainBox,contentBox); this._tragScroll(scrollDiv,mainBox,contentBox); this._wheelChange(scrollDiv,mainBox,contentBox); this._clickScroll(scrollDiv,mainBox,contentBox); }, //创建滚动条 _createScroll:function(mainBox,className){ var _scrollBox=doc.createElement('div') var _scroll=doc.createElement('div'); var span=doc.createElement('span'); _scrollBox.appendChild(_scroll); _scroll.appendChild(span); _scroll.className=className; mainBox.appendChild(_scrollBox); return _scroll; }, //调整滚动条 _resizeScorll:function(element,mainBox,contentBox){ var p=element.parentNode; var conHeight=contentBox.offsetHeight; var _width=mainBox.clientWidth; var _height=mainBox.clientHeight; var _scrollWidth=element.offsetWidth; var _left=_width-_scrollWidth; p.style.width=_scrollWidth+"px"; p.style.height=_height+"px"; p.style.left=_left+"px"; p.style.position="absolute"; p.style.background="#ccc"; contentBox.style.width=(mainBox.offsetWidth-_scrollWidth)+"px"; var _scrollHeight=parseInt(_height*(_height/conHeight)); if(_scrollHeight>=mainBox.clientHeight){ element.parentNode.style.display="none"; } element.style.height=_scrollHeight+"px"; }, //拖动滚动条 _tragScroll:function(element,mainBox,contentBox){ var mainHeight=mainBox.clientHeight; element.onmousedown=function(event){ var _this=this; var _scrollTop=element.offsetTop; var e=event||window.event; var top=e.clientY; //this.onmousemove=scrollGo; document.onmousemove=scrollGo; document.onmouseup=function(event){ this.onmousemove=null; } function scrollGo(event){ var e=event||window.event; var _top=e.clientY; var _t=_top-top+_scrollTop; if(_t>(mainHeight-element.offsetHeight)){ _t=mainHeight-element.offsetHeight; } if(_t<=0){ _t=0; } element.style.top=_t+"px"; contentBox.style.top=-_t*(contentBox.offsetHeight/mainBox.offsetHeight)+"px"; _wheelData=_t; } } element.onmouseover=function(){ this.style.background="#444"; } element.onmouseout=function(){ this.style.background="#666"; } }, //鼠标滚轮滚动，滚动条滚动 _wheelChange:function(element,mainBox,contentBox){ var node=typeof mainBox=="string"?$(mainBox):mainBox; var flag=0,rate=0,wheelFlag=0; if(node){ mouseWheel(node,function(data){ wheelFlag+=data; if(_wheelData>=0){ flag=_wheelData; element.style.top=flag+"px"; wheelFlag=_wheelData*12; _wheelData=-1; }else{ flag=wheelFlag/12; } if(flag<=0){ flag=0; wheelFlag=0; } if(flag>=(mainBox.offsetHeight-element.offsetHeight)){ flag=(mainBox.clientHeight-element.offsetHeight); wheelFlag=(mainBox.clientHeight-element.offsetHeight)*12; } element.style.top=flag+"px"; contentBox.style.top=-flag*(contentBox.offsetHeight/mainBox.offsetHeight)+"px"; }); } }, _clickScroll:function(element,mainBox,contentBox){ var p=element.parentNode; p.onclick=function(event){ var e=event||window.event; var t=e.target||e.srcElement; var sTop=document.documentElement.scrollTop>0?document.documentElement.scrollTop:document.body.scrollTop; var top=mainBox.offsetTop; var _top=e.clientY+sTop-top-element.offsetHeight/2; if(_top<=0){ _top=0; } if(_top>=(mainBox.clientHeight-element.offsetHeight)){ _top=mainBox.clientHeight-element.offsetHeight; } if(t!=element){ element.style.top=_top+"px"; contentBox.style.top=-_top*(contentBox.offsetHeight/mainBox.offsetHeight)+"px"; _wheelData=_top; } } }}new addScroll('mainBox','content','scrollDiv');</script></body></html>

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