docs

Expo Documentation

This is the public documentation for Expo, its SDK, client and services.

You can access this documentation online at https://docs.expo.io/. It's built using next.js on top of the https://github.com/zeit/docs codebase.

Contributors: Please make sure that you edit the docs in the pages/versions/unversioned directory if you want your changes to apply to the next SDK version too!

Running Locally

Download the copy of this repository.

git clone https://github.com/expo/expo.git

Then cd into the docs directory and install dependencies with:

yarn

Then you can run the app with (make sure you have no server running on port 3002):

yarn run dev

Now the documentation is running at http://localhost:3002

Running in production mode

yarn run export
yarn run export-server

Editing Docs Content

You can find the source of the documentation inside the pages/versions directory. Documentation is mostly written in markdown with the help of some React components (for Snack embeds, etc). The routes and navbar are automatically inferred from the directory structure within versions.

Editing Code

The docs are written with Next.js and TypeScript. If you need to make code changes, follow steps from the Running locally section, then open a separate terminal and run the TypeScript compiler in watch mode - it will watch your code changes and notify you about errors.

yarn watch

When you are done, you should run prettier to format your code. Also, don't forget to run tests and linter before committing your changes.

yarn prettier
yarn test
yarn lint

Internal linking

If you need to link from one MDX file to another, please use the path-reference to this file including extension. This allows us to automatically validate these links and see if the file and/or headers still exists.

• from: tutorial/button.md, to: /workflow/guides/ -> ../workflow/guides.md
• from: index.md, to: /guides/errors/#tracking-js-errors -> ./guides/errors.md#tracking-js-errors (or without ./)

You can validate all current links by running $ yarn lint-links.

Redirects

Server-side redirects

These redirects are limited in their expresiveness - you can map a path to another path, but no regular expressions or anything are supported. See client-side redirects for more of that. Server-side redirects are re-created on each run of deploy.sh.

We currently do two client-side redirects, using meta tags with http-equiv="refresh":

• / -> /versions/latest/
• /versions -> /versions/latest

This method is not great for accessibility and should be avoided where possible.

Client-side redirects

Use these for more complex rules than one-to-one path-to-path redirect mapping. For example, we use client-side redirects to strip the .html extension off, and to identify if the request is for a version of the documentation that we no longer support.

You can add your own client-side redirect rules in pages/_error.js.

Adding Images and Assets

You can add images and assets to the public/static directory. They'll be served by the production and staging servers at /static.

New Components

Always try to use the existing components and features in markdown. Create a new component or use a component from NPM, unless there is no other option.

Quirks

• You can't have curly brace without quotes: `{}` -> {}
• Make sure to leave a empty newline between a table and following content

A note about versioning

Expo's SDK is versioned so that apps made on old SDKs are still supported when new SDKs are relased. The website documents previous SDK versions too.

Version names correspond to directory names under versions.

unversioned is a special version for the next SDK release. It is not included in production output. Additionally, any versions greater than the package.json version number are not included in production output, so that it's possible to generate, test, and make changes to new SDK version docs during the release process.

latest is an untracked folder which duplicates the contents of the folder matching the version number in package.json.

Sometimes you want to make an edit in version X and have that edit also be applied in versions Y, Z, ... (say, when you're fixing documentation for an API call that existed in old versions too). You can use the ./scripts/versionpatch.sh utility to apply your git diff in one version in other versions. For example, to update the docs in unversioned then apply it on v8.0.0 and v7.0.0, you'd do the following after editing the docs in unversioned such that it shows up in git diff:

./scripts/versionpatch.sh unversioned v8.0.0 v7.0.0

Any changes in your git diff outside the unversioned directory are ignored so don't worry if you have code changes or such elsewhere.

Updating latest version of docs

When we release a new SDK, we copy the unversioned directory, and rename it to the new version. Latest version of docs is read from package.json so make sure to update the version key there as well. However, if you update the version key there, you need to rm -rf node_modules/.cache/ before the change is picked up (why? read this).

Make sure to also grab the upgrade instructions from the release notes blog post and put them in upgrading-expo-sdk-walkthrough.md.

That's all you need to do. The versions directory is listed on server start to find all available versions. The routes and navbar contents are automatically inferred from the directory structure within versions.

Because the navbar is automatically generated from the directory structure, the default ordering of the links under each section is alphabetical. However, for many sections, this is not ideal UX. So, if you wish to override the alphabetical ordering, manipulate page titles in navigation.js.

Syncing app.json / app.config.js with the schema

To render the app.json / app.config.js properties table, we currently store a local copy of the appropriate version of the schema.

If the schema is updated, in order to sync and rewrite our local copy, run yarn run schema-sync 39 (or relevant version number) or yarn run schema-sync unversioned.

Importing from the React Native docs

You can import the React Native docs in an automated way into these docs.

1. Update the react-native-website submodule here
2. yarn run import-react-native-docs

This will write all the relevant RN doc stuff into the unversioned version directory. You may need to tweak the script as the source docs change; the script hackily translates between the different forms of markdown that have different quirks.

The React Native docs are actually versioned but we currently read off of master.

TODOs: - Handle image sizing in imports better - Read from the appropriate version (configurable) of the React Native docs, not just master - Make Snack embeds work; these are marked in some of the React Native docs but they are just imported as plain JS code blocks