描述：
自定义滚动条的实现
效果：
实现：
<!DOCTYPE html>
<html lang="">
<head>
<meta charset="utf-8">
<title></title>
<style>
* {margin: 0;padding: 0;}
html,body { width: 100%;height: 100%;}
#box { width: 100%; height: 100%; overflow: hidden;}
/*一个个划过去的页面块*/
.ball {
width: 100%;
height: 500px;
font-size:100px;
font-weight:bold;
color: skyblue;
text-align: center;
line-height:500px;
}
/*//滚动栏*/
#scroll {
width: 20px; height: 96%;
position: fixed; top: 2%; right: 5px;
border-radius: 10px; background-color: rgba(235, 233, 233, 0.5);
z-index: 9998; opacity: 0;
}
/*//滚动栏上的小长条*/
#scrollBar {
position: absolute; z-index: 1;/*//定在上面*/
width: 20px; height: 40px;
border-radius: 10px;
left: 0; top: 0; background-color: red;opacity: 0.6;
}
</style>
</head>
<body style="overflow:hidden;">
<div id="box">
<div id="content">
<!--//营造div色块交替的感觉-->
<p class="ball" style="background-color:#656565;">1</p>
<p class="ball" style="background-color:#ffffff;">2</p>
<p class="ball" style="background-color:#656565;">3</p>
<p class="ball" style="background-color:#ffffff;">4</p>
<p class="ball" style="background-color:#656565;">5</p>
<p class="ball" style="background-color:#ffffff;">6</p>
</div>
</div>
<div id="scroll">
<div id="scrollBar"></div>
</div>
</body>
</html>
<script type="text/javascript">
var content = document.getElementById("content");
var box = document.getElementById("box");
var scroll = document.getElementById("scroll");
var scrollBar = document.getElementById("scrollBar");
var Step = {
value : 0,
size : 20,
maxVal : Math.ceil((content.offsetHeight-document.body.offsetHeight)/20),
getCurrentVal:function(){
return this.value;
},
next:function(){
if(this.value==this.maxVal) return;
this.value++;
},
pre:function(){
if(this.value==0) return;
this.value--;
},
getDistance:function(){
return this.getCurrentVal()*this.size;
},
update:function(){
this.maxVal = Math.ceil((content.offsetHeight-document.body.offsetHeight)/this.size);
}
}
window.addEventListener("resize",function(){
Step.update();
});
box.addEventListener("DOMMouseScroll",scrollfunc);
box.addEventListener("mousewheel", scrollfunc);
function scrollfunc(e){
if(e.type=="mousewheel"){ //非FF
e.wheelDelta<0?Step.next():Step.pre();
} else { //FF
e.detail>0?Step.next():Step.pre();
}
document.title = Step.getCurrentVal();
box.scrollTop = Math.min(Step.getDistance(),content.offsetHeight-document.body.offsetHeight);
//计算滚动比例
var percent = box.scrollTop/(content.offsetHeight-document.body.offsetHeight);
//显示滚动条
scroll.style.opacity = 100;
//计算滚动条的位置
scrollBar.style.top = (scroll.offsetHeight-scrollBar.offsetHeight)*percent + "px";
}
</script>
