JS案例：拖拽音量调节效果

向右看齐 2023-07-07 08:55 15阅读 0赞

用原生js做了一个拖拽调节音量

效果是这样的：（拖动时音量随两个圆形交集面积增大而增大）

![20200222153956378.gif][]

**源码：**[https://gitee.com/DieHunter/myCode/tree/master/music][https_gitee.com_DieHunter_myCode_tree_master_music]

html部分：

<!DOCTYPE html>
    <html lang="en">
    
    <head>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <meta http-equiv="X-UA-Compatible" content="ie=edge">
        <title>Document</title>
        <link rel="stylesheet" href="index.css">
    </head>
    
    <body>
        <audio id="audio" autoplay>
            <source src="./1.mp3" type="audio/mpeg">
        </audio>
        <div class="vol left" id="leftBox"></div>
        <div class="vol right" id="rightBox"></div>
        <script src="index.js"></script>
    </body>
    
    </html>

css部分：

* {
        margin: 0;
        padding: 0;
    }
    
    body {
        background: rgb(28, 160, 210);
    }
    
    .vol {
        width: 200px;
        height: 200px;
        position: absolute;
        border-radius: 100px;
    }
    
    .left {
        left: 500px;
        top: 100px;
        background: rgb(250, 242, 107);
    }
    
    .right {
        left: 800px;
        top: 100px;
        background: rgba(250, 242, 107, 100);
        z-index: 1;
    }

js部分：

var audio;
    init()//入口函数
    
    function init() {
        audio = document.getElementById("audio");//初始化播放器控件
        audio.volume = 0;//将控件音量初始值设置0
        mouseMove(rightBox, document)
    }
    
    function mouseMove(ele, parent) {
        ele.addEventListener('mousedown', moveHandler);//鼠标右击时触发moveHandler方法
        ele.style.position = 'absolute';
        ele.parent = parent;//传递父元素（可省略）
    }
    
    function moveHandler(e) {//moveHandler是个回调函数，鼠标按下，移动，松开都会触发，根据event的type判断事件类型
        if (e.preventDefault) {//取消系统默认事件
            e.preventDefault();
        } else {
            e.returnValue = false;
        }
        if (e.type === 'mousedown') {
            audio.play()//按下时开始播放音乐
            // 下面将被点击的元素及元素在X方向的偏移通过父元素传递（放入内存中）
            this.parent.ele = this;
            this.parent.point = {
                x: e.offsetX
            }
            // 为元素添加鼠标移动和松开事件
            this.parent.addEventListener('mousemove', moveHandler);
            this.addEventListener('mouseup', moveHandler);
        } else if (e.type === 'mousemove') {
            if (rightBox.offsetLeft - leftBox.offsetLeft >= 200 || rightBox.offsetLeft - leftBox.offsetLeft <= -200) {//当被移动元素与另一个元素无交集时，改变样式，使音量为0
                audio.volume = 0;
                document.body.style.background = 'rgb(28,160,210)'
                rightBox.style.background = 'rgba(250, 242, 107, 100)';
            } else {//当被移动元素与另一个元素有交集时，改变样式为渐变，使音量为相交面积的百分比（这里是两圆心之间的距离）
                var count = 1 - Math.abs(rightBox.offsetLeft - leftBox.offsetLeft) / 200;
                audio.volume = count
                document.body.style.background = `rgb(${28+50*count},${160-136*count},${210-133*count})`
                rightBox.style.background = `rgb(${28+50*count},${160-136*count},${210-133*count})`;
            }
            this.ele.style.left = e.x - this.point.x + "px";
        } else if (e.type === 'mouseup') {
            // 鼠标松开时释放内存及事件监听
            this.parent.removeEventListener("mousemove", moveHandler);
            this.parent.ele = null;
            this.parent.point = null;
        }
    }

[20200222153956378.gif]: https://img-blog.csdnimg.cn/20200222153956378.gif
[https_gitee.com_DieHunter_myCode_tree_master_music]: https://gitee.com/DieHunter/myCode/tree/master/music