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Use the more verbose fragment syntax to add a key attribute to a React fragment, for example <React.Fragment key={key}>.

The more verbose syntax achieves the same result—grouping a list of elements without adding extra nodes to the DOM.

import React from 'react';

const App = () => {
  const arr = ['Austria', 'Belgium', 'Canada'];

  return (
    <div>
      {arr.map((element, key) => {
        return (
          <React.Fragment key={key}>
            <h2>key: {key}</h2>
            <h2>element: {element}</h2>
            <hr />
          </React.Fragment>
        );
      })}
    </div>
  );
};

export default App;

We used a more verbose syntax for React fragments to be able to add key attributes to fragments.

Fragments are used when we need to group sublists without adding extra nodes to the DOM.

If we use the shorthand syntax for fragments <> </>, we won't be able to pass any properties to the fragment.

We can also import the Fragment element from React without having to React.Fragmentaccess it like .

// 👇️ 仅导入 Fragment
import {Fragment} from 'react';

const App = () => {
  const arr = ['Austria', 'Belgium', 'Canada'];

  return (
    <div>
      {arr.map((element, key) => {
        return (
          <Fragment key={key}>
            <h2>key: {key}</h2>
            <h2>element: {element}</h2>
            <hr />
          </Fragment>
        );
      })}
    </div>
  );
};

export default App;

This code example achieves the same result, but instead of importing the React namespace object, we only import the Fragment element.