原生js实现vue的数据双向绑定

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

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <input type="text" id="B"></input><br />
    <span id="S">{{textModel}}</span>
    <script>
        let mod = {}
        Object.defineProperty(mod, 'textModel', {
            set: function (arg) {
                document.getElementById('S').innerHTML = arg
                document.getElementById('B').value = arg
            }
        })
        document.getElementById('B').onkeyup = function (params) {
            console.log(mod)
            mod.textModel = params.target.value
        }
        mod.textModel = ""
    </script>
</body>

</html>