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When we try to export an anonymous function using default export, it results in the warning “Unexpected default export of anonymous function.” To fix this error, you need to give the function a name before exporting it.

Here is an example of how this can result in a warning.

// 匿名函数的默认导出

// ⛔️ Unexpected default export of anonymous function
// eslint import/no-anonymous-default-export
export default function () {
  return <h1>hello world</h1>;
}

The problem here is that we are using default export to export the anonymous function.

To fix this error, you need to name the function before using the default export.

// 为正在导出的函数命名
export default function Header() {
  return <h1>hello world</h1>;
}

重要提示: If you want to export a variable (or arrow function) as a default export, you must declare it on the first line and export it on the next line. We cannot declare and default export a variable on the same line.

const Header = () => {
  return <h1>hello world</h1>;
};

export default Header;

Now we can still import the function using the default import.

import Header from './Header';

const App = () => (
  <div>
    <Header />
  </div>
);

export default App;

This approach encourages reusing the same identifiers when exporting and importing functions.

By default, eslint rules will warn us about anonymous default exports of all types, such as arrays, functions, classes, objects, etc.

If you want to disable a single line rule, you can use comment.

// eslint-disable-next-line import/no-anonymous-default-export
export default function () {
  return <h1>hello world</h1>;
}

The comment should be placed just above the code with the anonymous default export.

Optionally, we can update what import/no-anonymous-default-exportthe rule should .eslintrccheck for in the file.

The options section of the Github repository shows the full default configuration for the rule, which we can .eslintrctweak in the rule object in our ./configure file.