Javascript实现鼠标移入方向感知

function getDir(ev, ele) {
      var l = ele.getBoundingClientRect().left;
      var t = ele.getBoundingClientRect().top;
      var w = ele.getBoundingClientRect().width;
      var h = ele.getBoundingClientRect().height;
      var x = (ev.clientX - l - w / 2) * (w > h "htmlcode">

<div id="container">
    <img src="/UploadFiles/2021-04-02/bg.jpg">

CSS:


*{
  margin: 0;
  padding: 0;
}

#container{
  width: 400px;
  height: 200px;
  position: relative;
  margin-top: 100px;
  margin-left: 200px;
  overflow: hidden;
  
}
#container img{
  width: 100%;
  height: 100%;
  transition: 0.5s;
}
#container p{
  width: 100%;
  height: 100%;
  padding: 10px;
  box-sizing: border-box;
  position: absolute;
  left: 0;
  /* top: 0; */
  background: rgba(0, 0, 0, .7);
  color: #ccc;
  font-size: 14px;
  line-height: 24px;
  
}
#container:hover img{
  transform: scale(1.1);
}


JS:


window.onload = function () {
      var box = document.getElementById('container');
      var ps = document.getElementsByClassName('ps');
      var pos=[
        {left:0,top:'-100%'},
        {left:'100%',top:0},
        {left:0,top:'100%'},
        {left:'-100%',top:0}
      ]
      box.onmouseenter = function(ev){
        var dir = getDir(ev,this);
        ps[0].style.transition='';
        ps[0].style.left=pos[dir].left;
        ps[0].style.top=pos[dir].top;
        setTimeout(function(){
          ps[0].style.transition='.3s';
          ps[0].style.left=0;
          ps[0].style.top=0;
        },1000/60)
      }
      box.onmouseleave = function(ev){
        var dir = getDir(ev,this);
        setTimeout(function(){
          ps[0].style.transition='';
          ps[0].style.left=pos[dir].left;
          ps[0].style.top=pos[dir].top;
        },100)
      }
    }
    function getDir(ev, ele) {
      var l = ele.getBoundingClientRect().left;
      var t = ele.getBoundingClientRect().top;
      var w = ele.getBoundingClientRect().width;
      var h = ele.getBoundingClientRect().height;
      var x = (ev.clientX - l - w / 2) * (w > h ? (h / w) : 1);
      var y = (ev.clientY - t - h / 2) * (h > w ? (w / h) : 1);
      var deg = Math.atan2(y, x) / (Math.PI / 180);
      var d = (Math.round((deg + 180) / 90) + 3) % 4;
      return d;
      // d的值{上:0,右:1,下:2,左:3}
}


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