React Group Array Of Objects By Key

<!DOCTYPE html>
<html>

<body>
    <div id="app"></div>
    <script type="text/babel">
        const data = [
            { id: 1, name: 'John', category: 'A' },
            { id: 2, name: 'Jane', category: 'B' },
            { id: 3, name: 'Bob', category: 'A' },
            { id: 4, name: 'Alice', category: 'C' },
            { id: 5, name: 'Mike', category: 'B' },
        ]

return (
                <div className='container'>
                    <h2>React Js group array of object by key(category)</h2>
                    {Object.entries(groupedData).map(([category, items]) => (
                        <div key={category}>
                            <h3>{category}</h3>
                            <ul>
                                {items.map((item) => (
                                    <li key={item.id}>{item.name}</li>
                                ))}
                            </ul>
                        </div>
                    ))}
                </div>
            );
        }
        ReactDOM.render(<App />, document.getElementById("app"));
    </script>
    <style>
        * {
            box-sizing: border-box;
        }

.container {
            margin: 0 auto;
            width: 600px;
            text-align: center;
            box-shadow: 0 1px 2px 0 rgba(0, 0, 0, 0.12), 0 2px 4px 0 rgba(0, 0, 0, 0.24);
            padding: 20px;
        }

h3 {
            font-size: 20px;
            margin-bottom: 10px;
        }

ul {
            list-style-type: none;
            padding-left: 0;
        }

li {
            margin-bottom: 5px;
        }

li:before {
            content: "▸";
            margin-right: 5px;
            color: #999;
        }

li:last-child {
            margin-bottom: 0;
        }
    </style>
</body>

</html>