js原生实现div渐入渐出

Posted 2020-10-02 前端开发-阿锋

jq对渐入渐出进行封装，简单的使用连个方法就可以实现。fadeIn(),fadeOut();如果我们界面没有使用jq那么原生怎么实现呢？

我们讲解一下，这个原理。当我们要实现渐入的时候，首先是让隐藏的div慢慢的显示，通过让opacity慢慢从 0.0 （完全透明）到 1.0（完全不透明）。渐出就是逻辑反过来的。

下面我们直接贴代码：

css:

* {margin:0; padding:0}
body {font:12px Verdana,Arial; color:#777; background:#222}
a {color:#999; text-decoration:none}
a:hover {color:#bbb}
#wrapper {width:500px; margin:75px auto}
#buttons {height:35px}
.button {border:1px solid #eee; background:#ccc; border-radius:3px; -moz-border-radius:3px; padding:4px 0 5px; width:245px; text-align:center; cursor:pointer; float:left; color:#555}
.button:hover {border:1px solid #fff; background:#d9d9d9; color:#333}
.floatright {float:right}
#fade {opacity:0; filter:alpha(opacity=‘0‘) border-radius:3px; -moz-border-radius:3px; margin-bottom:10px; padding:9px 10px 0; height:26px; border:1px solid #548954; background:#355c33; color:#79af72; text-shadow:1px 1px #21341d}

html:

<div id="wrapper">
<div id="fade">javascript</div>
<div id="buttons">
 <div class="button" onclick="fadeEffect.init(‘fade‘, 1)">Fade In</div>
 <div class="button floatright" onclick="fadeEffect.init(‘fade‘, 0)">Fade Out</div>
</div>
</p>
</div>

js:

var fadeEffect=function(){
 return{
  init:function(id, flag, target){
   this.elem = document.getElementById(id);
   clearInterval(this.elem.si);
   this.target = target ? target : flag ? 100 : 0;
   this.flag = flag || -1;
   this.alpha = this.elem.style.opacity ? parseFloat(this.elem.style.opacity) * 100 : 0;
   this.si = setInterval(function(){fadeEffect.tween()}, 20);
  },
  tween:function(){
   if(this.alpha == this.target){
    clearInterval(this.si);
   }else{
    var value = Math.round(this.alpha + ((this.target - this.alpha) * .05)) + (1 * this.flag);
    this.elem.style.opacity = value / 100;
    this.elem.style.filter = ‘alpha(opacity=‘ + value + ‘)‘;
    this.alpha = value
   }
  }
 }
}();