How to operate JS to implement transparency gradient animation-JS Tutorial-php.cn

How to operate JS to implement transparency gradient animation

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Release： 2018-06-01 14:40:49

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This time I will show you how to operate JS to achieve transparency gradient animation. What are the precautions for operating JS to achieve transparency gradient animation? The following is a practical case, let’s take a look.

<!DOCTYPE html>
<html>
  <head>
  <meta charset="utf-8">
    <title>JS透明度变化效果</title>
    <style>
    body{
      margin: 0px;
      padding: 0px;
    }
    .redb{
      width:200px;
      height: 200px;
      background: red;
      filter:alpha(opacity=30);
      opacity: 0.3;
    }
    </style>
  </head>
  <body>
    <p class="redb" id="opbtn"></p>
    <script>
    window.onload = function(){
      var opp = document.getElementById("opbtn");
      opp.onmouseover = function(){
        startMove(100);
      }
      opp.onmouseout = function(){
        startMove(30);
      }
    }
    var timer = null;
    var alpha = 30;
    var speed = 0;
    function startMove(opTarget){
      clearInterval(timer);
      var opp = document.getElementById("opbtn");
      timer = setInterval(function(){
        if(alpha<opTarget){
          speed = 10;
        }
        else if(alpha>opTarget){
          speed = -10;
        }
        if(alpha==opTarget){
          clearInterval(timer);
        }
        else{
          alpha += speed;
          opp.style.opacity = alpha/100;
          opp.style.filter = 'alpha(opacity='+alpha+')';
        }
      },100);
    }
    </script>
  </body>
</html>

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Summary:

1. The difference between filter and opacity: w3c standard transparency is opacity, filter can only be used by IE, other browsers support opacity

2 . When changing the transparency, the transparency value cannot be obtained through a method similar to offsetLeft, so you need to create a separate variable
3. Don’t forget to assign the
timer to timer

I believe you have read the case in this article You have mastered the method. For more exciting information, please pay attention to other related articles on the php Chinese website!