JavaScript实现点击鼠标弹钢琴的效果

思路：图片设置宽900px，找到鼠标按下时的x坐标和img距离body的x坐标，两个值相减，然后除100取整，赋值给a，通过判断a的值来确定放出那个音乐。

完整代码：

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        img {
            width: 900px;
        }

        #box {
            margin: 100px auto;
            width: 900px;
            position: relative;
        }
    </style>
</head>

<body>
    <div id="box">
        //将图片路径替换成自己的
        <img src="./keys.png" alt="">
    </div>
    <script>
        var img = document.querySelector('img');
        var box = document.querySelector('#box');
        console.log(box, img);
        img.onmousedown = function (e) {

            var x = e.pageX - box.offsetLeft;
            console.log(x);
            var a = parseInt(x / 100);
            console.log(a);
                 //将mp3路径替换成自己的文件
            switch (a) {
                case 0:
                    var audio = new Audio('./钢琴9键-mp3/d1.mp3');
                    audio.play();
                    break;
                case 1:
                    var audio = new Audio('./钢琴9键-mp3/d2.mp3');
                    audio.play();
                    break;
                case 2:
                    var audio = new Audio('./钢琴9键-mp3/d3.mp3');
                    audio.play();
                    break;
                case 3:
                    var audio = new Audio('./钢琴9键-mp3/d4.mp3');
                    audio.play();
                    break;
                case 4:
                    var audio = new Audio('./钢琴9键-mp3/d5.mp3');
                    audio.play();
                    break;
                case 5:
                    var audio = new Audio('./钢琴9键-mp3/d6.mp3');
                    audio.play();
                    break;
                case 6:
                    var audio = new Audio('./钢琴9键-mp3/d7.mp3');
                    audio.play();
                    break;
                case 7:
                    var audio = new Audio('./钢琴9键-mp3/d8.mp3');
                    audio.play();
                    break;
                case 8:
                    var audio = new Audio('./钢琴9键-mp3/d9.mp3');
                    audio.play();
                    break;

            }

        }
    </script>
</body>

</html>

页面效果：