<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <style>
    *{
      border: 0;
      margin: 0;
      ">#f6f6f6;
    }
    img{
      float: left;
    }
  </style>
</head>
<body>
    <img src="images/00.png" alt="">
    <img src="images/00.png" alt="">
    <img src="images/00.png" alt="">
    <img src="images/00.png" alt="">
    <img src="images/00.png" alt="">
<script>
    var imgs = document.images;
    for (var i = 0; i < imgs.length; i++) {
        imgs[i].a = i;
        imgs[i].onmouseover = function () {
            // alert(123)
            for (var j = 0; j <= this.a; j++) {
                // alert(123);
                imgs[j].src = imgs[j].src.replace('00', '01')
                for (var k = 1; k <= this.a-1; k++) {
                    imgs[j].src = imgs[j].src.replace('01', '02')

                    for (var b = imgs.length + 1; b <= this.a + 2; b++) {
                        imgs[j].src = imgs[j].src.replace('02', '03')
                    }
                }
                if (this.a-imgs.length){
                    // alert(123)
                    imgs[j].onmouseout = function (){
                        // alert(123)
                        for(var j=0;j<=this.a;j++){
                            imgs[j].src = imgs[j].src.replace('01','00')
                            imgs[j].src = imgs[j].src.replace('02','00')
                            imgs[j].src = imgs[j].src.replace('03','00')
                            // alert(123)
                        }
                    }
                }
            }
        }
    }
</script>
</body>
</html>