js implements a method similar to the animate animation in jquery

2020-05-27 04:12:01
OfStack

This article demonstrates an example of how js can achieve an animate animation effect similar to that in jquery. Share with you for your reference. The specific analysis is as follows:

This example can realize the mouse move up, first the width change, then the height change, finally the transparency change, the mouse move out, then in turn change back effect.

Point 1:


startrun(obj,attr,target,fn)
box.onmouseover = function(){
startrun(box,"width",200,function(){
startrun(box,"height",200,function(){
startrun(box,"opacity","100")
});
});
}

As above, functions can also be used as arguments to achieve the effect of executing an action first and then another action.

Point 2:


if(cur == target){
clearInterval(obj.timer);
if(fn){
fn();
}
}

When the motion reaches the target point, the timer is turned off, and the new function can be executed.

Finally, add the code:


<!DOCTYPE html>
<html>
<head>
<meta charset="gb2312" />
<title> Headless document </title>
<style>
<!--
body{margin:0; padding:0; font:12px/1.5 arial;}
#box{width:100px; height:100px; position:absolute;
background:#06c; left:0;filter:alpha(opacity=30); opacity:0.3;}
-->
</style>
<script>
<!--
function getstyle(obj,name){
 if(obj.currentStyle){
  return obj.currentStyle[name];
 }else{
  return getComputedStyle(obj,false)[name];
 }
}
window.onload = function(){
 var box = document.getElementById("box");
 box.onmouseover = function(){
  startrun(box,"width",200,function(){
   startrun(box,"height",200,function(){
    startrun(box,"opacity","100")
   });
  });
 }
 box.onmouseout = function(){
  startrun(box,"height",100,function(){
   startrun(box,"width",100,function(){
    startrun(box,"opacity","30");
   });
  });
 }
}
function startrun(obj,attr,target,fn){
 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);
   if(fn){
    fn();
   }
  }else{
   if(attr == "opacity"){
    obj.style.filter = "alpha(opacity="+(cur+speed)+")";
    obj.style.opacity = (cur+speed)/100;
   }else{
   obj.style[attr] = cur + speed + "px";
   }
  }
 },30)
}
//-->
</script>
</head>
<body>
<div id="box">
</div>
</body>
</html>

I hope this article is helpful for you to design the javascript program.