dialog是html5.2的规范，浏览器兼容性比较差，常用的特性就这些，具体可以看看这里

<!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>
    <style>
        dialog {
            border-color: red;
        }

        dialog::backdrop {
            background: rgba(0, 0, 0, 0.3);
        }
    </style>
</head>

<body>
    <button id="btn">TEST</button>
    <dialog id="dialog">12
        <button id="close">close</button>
    </dialog>
    <script>
        var dialogEl = document.querySelector('#dialog');
        var btnEl = document.querySelector('#btn');
        var closeEl = document.querySelector('#close');

        btnEl.addEventListener('click', e => {
            // dialogEl.show(); // 打开dialog
            dialogEl.showModal(); // 打开dialog，有蒙版
        });

        closeEl.addEventListener('click', e => {
            dialogEl.close('testValue');
            console.log(dialogEl.returnValue) // 'testValue'
        });

        dialogEl.addEventListener('close', e => {
            console.log('close event')
        });

        dialogEl.addEventListener('cancel', e => {
            // 按下ESC同时也会触发close事件
            console.log('enter ESC key event')
            // 以下可选代码
            dialogEl.close('testValue2'); // 
            console.log(e.target.returnValue); // 'testValue2'
        });

    </script>
</body>

</html>

代码可以直接复制到这里在线运行调试