js根据鼠标方向划入遮罩层 | js根据鼠标方向划入遮罩层

js根据鼠标方向划入遮罩层:
<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title>Document</title>

</head>

<style>

    ul{

        overflow:hidden;

    }

    .game-list{

        float: left;

        width:296px;

        height:240px;

        border: 1px solid #cdcdcd;

        box-shadow: 0 10px 10px #e7e7e7;

        margin-left: 93px;

        margin-top:20px;

        position: relative;

        overflow: hidden;

    }

    .slidiv{

        position: absolute;

        height:240px;

        width:296px;

        background: rgba(9,9,9,0.5);

        position: absolute;

        left:-296px;

        top:0;

        text-align: center;

        color: #FFFFFF;

    }

    a{

        width:296px;

        height:240px;

        display: block;

    }

</style>

<body>

    <div>

       <ul>

            <li class="game-list">

                <a href="#">3131</a>

                <div class="slidiv">

                    <p>1</p>

                </div>

            </li>

        </ul>

    </div>

</body>

<script src="https://cdn.bootcss.com/jquery/3.2.1/jquery.min.js"></script>

<script>

slidiv()

function slidiv(){

    $(".game-list").bind("mouseenter mouseleave",  function(e) {

        var w = $(this).width();

        var h = $(this).height();

        //计算鼠标指针x,y位于当前元素比例的坐标位置

        var x = (e.pageX - this.offsetLeft - (w / 2)) * (w > h ? (h / w) : 1);

        var y = (e.pageY - this.offsetTop - (h / 2)) * (h > w ? (w / h) : 1);

        //得出四个方向的值（0，1，2，3）

        var direction = Math.round((((Math.atan2(y, x) * (180 / Math.PI)) + 180) / 90) + 3) % 4;

        this_slidiv = $(this).find('.slidiv');

        if(e.type == 'mouseenter'){

            switch(direction){

                case 0 :

                    this_slidiv.css({top:-h,left:"0px"});

                    break;

                case 1:

                    this_slidiv.css({top:"0px",left:w});

                    break;

                case 2:

                    this_slidiv.css({top:h,left:"0px"});

                    break;

                case 3:

                    this_slidiv.css({top:"0px",left:-w});

                    break;

            }

            this_slidiv.stop(true,true).animate({"top":"0px","left":"0px"},"fast");

        }else if(e.type == 'mouseleave'){

            switch(direction){

                case 0 :

                    this_slidiv.stop(true,true).animate({"top":-h},"fast");

                    break;

                case 1:

                    this_slidiv.stop(true,true).animate({"left":w},"fast");

                    break;

                case 2:

                    this_slidiv.stop(true,true).animate({"top":h},"fast");

                    break;

                case 3:

                    this_slidiv.stop(true,true).animate({"left":-w},"fast");

                    break;

            }

        }

    });

}

</script>

</html>