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JS implements transparency gradient function

php中世界最好的语言Original: 2018-05-14 14:36:482685browse

This time I will bring you JS to implement the transparency gradient function. What are the precautions for JS to implement the transparency gradient function? 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>

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!

JS implements transparency gradient function

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