js滚轮事件 自定义滚动条的实现

本文实例为大家分享了js自定义滚动条的实现的具体代码，供大家参考，具体内容如下

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>

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