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Recommend export = over export default in cjs declaration files #3322

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andrewbranch merged 3 commits into from
Feb 6, 2025
Merged

Recommend export = over export default in cjs declaration files #3322

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Recommend `export =` over `export default` in cjs declaration files
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13 changes: 2 additions & 11 deletions packages/documentation/copy/en/declaration-files/templates/module.d.ts.md
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Expand Up @@ -59,7 +59,7 @@ Which can be described by the following .d.ts:

```ts
declare const helloWorld: RegExp;
export default helloWorld;
export = helloWorld;
```

Or a number:
Expand All @@ -70,7 +70,7 @@ module.exports = 3.142;

```ts
declare const pi: number;
export default pi;
export = pi;
```

One style of exporting in CommonJS is to export a function.
Expand All @@ -87,15 +87,6 @@ module.exports = getArrayLength;

Which can be described with:

```ts
export default function getArrayLength(arr: any[]): number;
export const maxInterval: 12;
```

Note that using `export default` in your .d.ts files requires [`esModuleInterop: true`](/tsconfig#esModuleInterop) to work.
If you can't have `esModuleInterop: true` in your project, such as when you're submitting a PR to Definitely Typed, you'll have to use the `export=` syntax instead. This older syntax is harder to use but works everywhere.
Here's how the above example would have to be written using `export=`:

```ts
declare function getArrayLength(arr: any[]): number;
declare namespace getArrayLength {
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