This is documentation for the next SDK version. For up-to-date documentation, see the latest version (SDK 58).

Expo Constants

An API that provides system information that remains constant throughout the lifetime of your app's installation.

Android

iOS

tvOS

Web

Included in Expo Go

GitHub

npm

Changelog

expo-constants provides system information that remains constant throughout the lifetime of your app's installation.

Your app can read these values, but it cannot change them. The device and the operating system provide some of them, such as Constants.deviceName and Constants.systemFonts. Constants.expoConfig contains most of your app config. To pass your own values to your app, add them to the extra field of your app config. Then read them from Constants.expoConfig.extra.

Platform-specific values are in Constants.platform. For example, on iOS, Constants.platform.ios.buildNumber returns the build number of your app (it is null in Expo Go). For other device and app details, use expo-device and expo-application.

Installation

Terminal

- npx expo install expo-constants

- yarn expo install expo-constants

- pnpm expo install expo-constants

- bun expo install expo-constants

If you are installing this in an existing React Native app, make sure to install expo in your project.

API

import Constants from 'expo-constants';

Types

`AndroidManifest`

Android

Type: Record<string, any> extended by:

Property	Type	Description
versionCode	`number`	Deprecated: Use `expo-application`'s `Application.nativeBuildVersion`. The version code set by `android.versionCode` in app.json. The value is set to `null` in case you run your app in Expo Go.

`ClientScopingConfig`

Android

iOS

tvOS

Web

Type: ClientScopingConfig

`EASConfig`

Android

iOS

tvOS

Web

Type: EASConfig

`ExpoGoConfig`

Android

iOS

tvOS

Web

Type: ExpoGoConfig

`ExpoGoPackagerOpts`

Android

iOS

tvOS

Web

Type: ExpoGoPackagerOpts

`IOSManifest`

iOS

Type: Record<string, any> extended by:

Property	Type	Description
buildNumber	`string \| null`	The build number specified in the embedded Info.plist value for `CFBundleVersion` in this app. In a standalone app, you can set this with the `ios.buildNumber` value in app.json. This may differ from the value in `Constants.expoConfig.ios.buildNumber` because the manifest can be updated, whereas this value will never change for a given native binary. The value is set to `null` in case you run your app in Expo Go.
model	`string \| null`	Deprecated: Moved to `expo-device` as `Device.modelName`. The human-readable model name of this device. For example, `"iPhone 7 Plus"` if it can be determined, otherwise will be `null`.
platform	`string`	Deprecated: Use `expo-device`'s `Device.modelId`. The Apple internal model identifier for this device. Example `iPhone1,1`
systemVersion	`string`	Deprecated: Use `expo-device`'s `Device.osVersion`. The version of iOS running on this device. Example `10.3`
userInterfaceIdiom	`UserInterfaceIdiom`	Deprecated: Use `expo-device`'s `Device.getDeviceTypeAsync()`. The user interface idiom of the current device, such as whether the app is running on an iPhone, iPad, Mac or Apple TV.

`Manifest`

Android

iOS

tvOS

Web

Type: ExpoUpdatesManifest

`ManifestAsset`

Android

iOS

tvOS

Web

Type: ManifestAsset

`ManifestExtra`

Android

iOS

tvOS

Web

Type: ManifestExtra

`NativeConstants`

Android

iOS

tvOS

Web

Type: Record<string, any> extended by:

Property	Type	Description
appOwnership	`AppOwnership \| null`	Deprecated: Use `Constants.executionEnvironment` instead. Returns `expo` when running in Expo Go, otherwise `null`.
debugMode	`boolean`	Returns `true` when the app is running in debug mode (`__DEV__`). Otherwise, returns `false`.
deviceName(optional)	`string`	A human-readable name for the device type.
deviceYearClass	`number \| null`	Deprecated: Moved to `expo-device` as `Device.deviceYearClass`. The device year class of this device.
easConfig	`EASConfig \| null`	The standard Expo Services config object populated when using Expo Services.
executionEnvironment	`ExecutionEnvironment`	Returns the current execution environment.
experienceUrl	`string`	-
expoConfig	`ExpoConfig & { hostUri: string } \| null`	The resolved app config, without fields such as `android.config` and `ios.config` that the public config filters out. In a build, this is the config embedded at build time. When the app runs an update, this is the config that comes with that update. During development, this is the config that the development server serves. To print it for your project, run `npx expo config --type public`.
expoGoConfig	`ExpoGoConfig \| null`	The standard Expo Go config object populated when running in Expo Go.
expoRuntimeVersion	`string \| null`	Nullable only on the web.
expoVersion	`string \| null`	The version string of the Expo Go app currently running. Returns `null` in existing React Native projects and on web.
getWebViewUserAgentAsync	`() => Promise<string \| null>`	Gets the user agent string which would be included in requests sent by a web view running on this device. This is probably not the same user agent you might be providing in your JS `fetch` requests.
intentUri(optional)	`string`	-
isDetached(optional)	`boolean`	-
isHeadless	`boolean`	Returns `true` if the app is running in headless mode. Otherwise, returns `false`.
linkingUri	`string`	-
manifest2	`ExpoUpdatesManifest \| null`	Manifest for Expo apps using modern Expo Updates from a remote source, such as apps that use Expo Update. `Constants.expoConfig` should be used for accessing the Expo config object.
platform(optional)	`PlatformManifest`	Returns the specific platform manifest object. Note: This is distinct from the `manifest` and `manifest2`.
sessionId	`string`	A string that is unique to the current session of your app. It is different across apps and across multiple launches of the same app.
statusBarHeight	`number`	The default status bar height for the device. Does not factor in changes when location tracking is in use or a phone call is active.
systemFonts	`string[]`	A list of the system font names available on the current device.
systemVersion(optional)	`number`	-

`PlatformManifest`

Android

iOS

tvOS

Web

Type: Record<string, any> extended by:

Property	Type	Description
android(optional)	`AndroidManifest`	-
detach(optional)	`{ scheme: string }`	-
developer(optional)	`string`	-
hostUri(optional)	`string`	-
ios(optional)	`IOSManifest`	-
scheme(optional)	`string`	-
web(optional)	`WebManifest`	-

`WebManifest`

Web

Type: Record<string, any>

Enums

`AppOwnership`

Android

iOS

tvOS

Web

Deprecated: Use Constants.executionEnvironment instead.

`Expo`

AppOwnership.Expo ＝ "expo"

The experience is running inside the Expo Go app.

`ExecutionEnvironment`

Android

iOS

tvOS

Web

Identifies where the app's JavaScript bundle is currently running.

`Bare`

ExecutionEnvironment.Bare ＝ "bare"

A project that includes native project directories that you maintain directly in your existing React Native project.

`Standalone`

ExecutionEnvironment.Standalone ＝ "standalone"

Production/release build created with or without Expo Build.

`StoreClient`

ExecutionEnvironment.StoreClient ＝ "storeClient"

Expo Go or a development build built with expo-dev-client.

`UserInterfaceIdiom`

Android

iOS

tvOS

Web

Current supported values are handset, tablet, desktop and tv. CarPlay will show up as unsupported.

`Desktop`

UserInterfaceIdiom.Desktop ＝ "desktop"

`Handset`

UserInterfaceIdiom.Handset ＝ "handset"

`Tablet`

UserInterfaceIdiom.Tablet ＝ "tablet"

`TV`

UserInterfaceIdiom.TV ＝ "tv"

`Unsupported`

UserInterfaceIdiom.Unsupported ＝ "unsupported"