> This feature is exclusive of `next export`. Please refer to [Static HTML export](/docs/advanced-features/static-html-export.md) if you want to learn more about it.
The pages will then be exported as HTML files, for example, `/about` will become `/about.html`.
`exportPathMap` is an `async` function that receives 2 arguments: the first one is `defaultPathMap`, which is the default map used by Next.js. The second argument is an object with:
-`dev` - `true` when `exportPathMap` is being called in development. `false` when running `next export`. In development `exportPathMap` is used to define routes.
-`dir` - Absolute path to the project directory
-`outDir` - Absolute path to the `out/` directory (configurable with `-o`). When `dev` is `true` the value of `outDir` will be `null`.
-`distDir` - Absolute path to the `.next/` directory (configurable with the [`distDir`](/docs/api-reference/next.config.js/setting-a-custom-build-directory.md) config)
-`buildId` - The generated build id
The returned object is a map of pages where the `key` is the `pathname` and the `value` is an object that accepts the following fields:
-`page`: `String` - the page inside the `pages` directory to render
-`query`: `Object` - the `query` object passed to `getInitialProps` when prerendering. Defaults to `{}`
> The exported `pathname` can also be a filename (for example, `/readme.md`), but you may need to set the `Content-Type` header to `text/html` when serving its content if it is different than `.html`.
## Adding a trailing slash
It is possible to configure Next.js to export pages as `index.html` files and require trailing slashes, `/about` becomes `/about/index.html` and is routable via `/about/`. This was the default behavior prior to Next.js 9.
To switch back and add a trailing slash, open `next.config.js` and enable the `exportTrailingSlash` config: