javascript缓冲运动代码实例

快乐打工仔 分类:实例代码

本章节分享一段代码实例,它实现了缓冲运动效果。

在编码中,匀速运动是比较简单的,但是在某些效果中并不够人性化。

而缓冲运动比较平滑,用户感受也就比较好,下面就是一段这方面的简单代码实例。

代码如下:

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="author" content="http://www.pipipi.net/" />
<title>犀牛前端部落</title>
<style>
body, ul, li{
  margin:0;
  padding 0;
}
#runs li{
  width:80px;
  height:80px;
  background:#06c;
  list-style:none;
  margin:10px;
  border:1px solid #000;
  filter:alpha(opacity=30);
  opacity:0.3;
}
</style>
<script>
window.onload = function(){
  var runs = document.getElementById("runs");
  var runs_li = runs.getElementsByTagName("li");
  runs_li[0].onmouseover = function(){
    startrun(this,"width",300);
  }
  runs_li[0].onmouseout = function(){
    startrun(this,"width",80);
  }
  runs_li[1].onmouseover = function(){
    startrun(this,"height",300);
  }
  runs_li[1].onmouseout = function(){
    startrun(this,"height",80);
  }
  runs_li[2].onmouseover = function(){
    startrun(this,"fontSize",50);
  }
  runs_li[2].onmouseout = function(){
    startrun(this,"fontSize",14);
  }
  runs_li[3].onmouseover = function(){
    startrun(this,"opacity",100);
  }
  runs_li[3].onmouseout = function(){
    startrun(this,"opacity",30);
  }
}
function startrun(obj,attr,target){
  clearInterval(obj.timer);
  obj.timer = setInterval(function(){
    var cur = 0;
    if(attr == "opacity"){
      cur = Math.round(parseFloat(getstyle(obj,attr))*100);
    }
    else{
      cur = parseInt(getstyle(obj,attr));
    }
    var speed = (target - cur)/8;
    speed = speed>0?Math.ceil(speed):Math.floor(speed);
    
    if(cur == target){
      clearInterval(obj.timer);
    }
    else{
      if(attr == "opacity"){
        obj.style.filter='alpha(opacity='+(cur+speed)+')';
        obj.style.opacity=(cur+speed)/100;
      }
      else{
        obj.style = cur+speed+"px";
      }
    }
  },30);
}
function getstyle(obj,name){
  if(obj.currentStyle){
    return obj.currentStyle[name];
  }
  else{
    return getComputedStyle(obj,false)[name];
  }
}
</script>
</head>
<body>
<ul id="runs">
  <li style="top:0">1</li>
  <li style="top:90px;">2</li>
  <li style="top:180px;">3</li>
  <li style="top:270px;">4</li>
</ul>
</body>
</html>

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