Expo WebBrowserA library that provides access to the system's web browser and supports handling redirects.
expo-web-browser provides access to the system's web browser and supports handling redirects. On Android, it uses ChromeCustomTabs and on iOS, it uses SFSafariViewController or ASWebAuthenticationSession, depending on the method you call. As of iOS 11, SFSafariViewController no longer shares cookies with Safari, so if you are using WebBrowser for authentication you will want to use WebBrowser.openAuthSessionAsync, and if you just want to open a webpage (such as your app privacy policy), then use WebBrowser.openBrowserAsync.
Installation
- npx expo install expo-web-browserIf you are installing this in an existing React Native app, start by installing expo in your project. Then, follow the additional instructions as mentioned by the library's README under "Installation in bare React Native projects" section.
Usage
import { useState } from 'react';
import { Button, Text, View, StyleSheet } from 'react-native';
import * as WebBrowser from 'expo-web-browser';
%%placeholder-start%%%%placeholder-end%%import Constants from 'expo-constants';
export default function App() {
const [result, setResult] = useState(null);
const _handlePressButtonAsync = async () => {
let result = await WebBrowser.openBrowserAsync('https://expo.dev');
setResult(result);
};
return (
<View style={styles.container}>
<Button title="Open WebBrowser" onPress={_handlePressButtonAsync} />
<Text>{result && JSON.stringify(result)}</Text>
</View>
);
}
const styles = StyleSheet.create({
container: {
flex: 1,
alignItems: 'center',
justifyContent: 'center',
paddingTop: Constants.statusBarHeight,
backgroundColor: '#ecf0f1',
},
});
Handling deep links from the WebBrowser
If your project uses Expo Router, deep links are handled automatically.
If you use the WebBrowser window for authentication or another use case where you want to pass information back into your app through a deep link, add a handler with Linking.addEventListener before opening the browser. When the listener fires, you should call dismissBrowser. It will not automatically be dismissed when a deep link is handled. Aside from that, redirects from WebBrowser work the same as other deep links. Read more about it in Linking.
API
import * as WebBrowser from 'expo-web-browser';
Methods
| Parameter | Type | Description |
|---|---|---|
| browserPackage(optional) | string | Package of browser to be cooled. If not set, preferred browser will be used. |
This methods removes all bindings to services created by warmUpAsync
or mayInitWithUrlAsync. You should call
this method once you don't need them to avoid potential memory leaks. However, those binding
would be cleared once your application is destroyed, which might be sufficient in most cases.
Promise<WebBrowserCoolDownResult>The promise which fulfils with WebBrowserCoolDownResult when cooling is performed, or
an empty object when there was no connection to be dismissed.
Dismisses the current authentication session. On web, it will close the popup window associated with auth process.
voidThe void on the successful attempt or throws an error if dismiss functionality is not available.
Dismisses the presented web browser.
Promise<{
type: WebBrowserResultType.DISMISS
}>The promise that resolves with { type: 'dismiss' } on the successful attempt or throws an error if dismiss functionality is not available.
Returns a list of applications package names supporting Custom Tabs, Custom Tabs
service, user chosen and preferred one. This may not be fully reliable, since it uses
PackageManager.getResolvingActivities under the hood. (For example, some browsers might not be
present in browserPackages list once another browser is set to default.)
Promise<WebBrowserCustomTabsResults>The promise which fulfils with WebBrowserCustomTabsResults object.
| Parameter | Type |
|---|---|
| options(optional) | WebBrowserCompleteAuthSessionOptions |
Possibly completes an authentication session on web in a window popup. The method should be invoked on the page that the window redirects to.
Returns an object with message about why the redirect failed or succeeded:
If type is set to failed, the reason depends on the message:
Not supported on this platform: If the platform doesn't support this method (Android, iOS).Cannot use expo-web-browser in a non-browser environment: If the code was executed in an SSR or node environment.No auth session is currently in progress: (the cached state wasn't found in local storage). This can happen if the window redirects to an origin (website) that is different to the initial website origin. If this happens in development, it may be because the auth started on localhost and finished on your computer port (Ex:128.0.0.*). This is controlled by theredirectUrlandreturnUrl.Current URL "<URL>" and original redirect URL "<URL>" do not match: This can occur when the redirect URL doesn't match what was initial defined as thereturnUrl. You can skip this test in development by passing{ skipRedirectCheck: true }to the function.
If type is set to success, the parent window will attempt to close the child window immediately.
If the error ERR_WEB_BROWSER_REDIRECT was thrown, it may mean that the parent window was
reloaded before the auth was completed. In this case you'll need to close the child window manually.
| Parameter | Type | Description |
|---|---|---|
| url | string | The url of page that is likely to be loaded first when opening browser. |
| browserPackage(optional) | string | Package of browser to be informed. If not set, preferred browser will be used. |
This method initiates (if needed) CustomTabsSession
and calls its mayLaunchUrl method for browser specified by the package.
Promise<WebBrowserMayInitWithUrlResult>A promise which fulfils with WebBrowserMayInitWithUrlResult object.
| Parameter | Type | Description |
|---|---|---|
| url | string | The url to open in the web browser. This should be a login page. |
| redirectUrl(optional) | null | string | Optional - The url to deep link back into your app.
On web, this defaults to the output of |
| options(optional) | AuthSessionOpenOptions | Optional - An object extending the Default: {} |
On Android:
This will be done using a "custom Chrome tabs" browser, AppState, and Linking APIs.
On iOS:
Opens the url with Safari in a modal using ASWebAuthenticationSession. The user will be asked
whether to allow the app to authenticate using the given url.
To handle redirection back to the mobile application, the redirect URI set in the authentication server
has to use the protocol provided as the scheme in app.json expo.scheme.
For example, demo:// not https:// protocol.
Using Linking.addEventListener is not needed and can have side effects.
On web:
This API can only be used in a secure environment (localhost/https). to test this. Otherwise, an error with code
ERR_WEB_BROWSER_CRYPTOwill be thrown. This will use the browser'swindow.open()API.
- Desktop: This will create a new web popup window in the browser that can be closed later using
WebBrowser.maybeCompleteAuthSession(). - Mobile: This will open a new tab in the browser which can be closed using
WebBrowser.maybeCompleteAuthSession().
How this works on web:
- A crypto state will be created for verifying the redirect.
- This means you need to run with
npx expo start --https
- This means you need to run with
- The state will be added to the window's
localstorage. This ensures that auth cannot complete unless it's done from a page running with the same origin as it was started. Ex: ifopenAuthSessionAsyncis invoked onhttps://localhost:19006, thenmaybeCompleteAuthSessionmust be invoked on a page hosted from the originhttps://localhost:19006. Using a different website, or even a different host likehttps://128.0.0.*:19006for example will not work. - A timer will be started to check for every 1000 milliseconds (1 second) to detect if the window
has been closed by the user. If this happens then a promise will resolve with
{ type: 'dismiss' }.
On mobile web, Chrome and Safari will block any call to
window.open()which takes too long to fire after a user interaction. This method must be invoked immediately after a user interaction. If the event is blocked, an error with codeERR_WEB_BROWSER_BLOCKEDwill be thrown.
Promise<WebBrowserAuthSessionResult>- If the user does not permit the application to authenticate with the given url, the Promise fulfills with
{ type: 'cancel' }object. - If the user closed the web browser, the Promise fulfills with
{ type: 'cancel' }object. - If the browser is closed using
dismissBrowser, the Promise fulfills with{ type: 'dismiss' }object.
| Parameter | Type | Description |
|---|---|---|
| url | string | The url to open in the web browser. |
| browserParams(optional) | WebBrowserOpenOptions | A dictionary of key-value pairs. Default: {} |
Opens the url with Safari in a modal on iOS using SFSafariViewController,
and Chrome in a new custom tab
on Android. On iOS, the modal Safari will not share cookies with the system Safari. If you need
this, use openAuthSessionAsync.
Promise<WebBrowserResult>The promise behaves differently based on the platform.
On Android promise resolves with { type: 'opened' } if we were able to open browser.
On iOS:
- If the user closed the web browser, the Promise resolves with
{ type: 'cancel' }. - If the browser is closed using
dismissBrowser, the Promise resolves with{ type: 'dismiss' }.
| Parameter | Type | Description |
|---|---|---|
| browserPackage(optional) | string | Package of browser to be warmed up. If not set, preferred browser will be warmed. |
This method calls warmUp method on CustomTabsClient
for specified package.
Promise<WebBrowserWarmUpResult>A promise which fulfils with WebBrowserWarmUpResult object.
Types
If there is no native AuthSession implementation available (which is the case on Android) the params inherited from
WebBrowserOpenOptions will be used in the browser polyfill. Otherwise, the browser parameters will be ignored.
Type: WebBrowserOpenOptions extended by:
| Property | Type | Description |
|---|---|---|
| preferEphemeralSession(optional) | boolean | Only for: iOS Determines whether the session should ask the browser for a private authentication session.
Set this to Default: false |
Literal Type: multiple types
Acceptable values are: WebBrowserRedirectResult | WebBrowserResult
| Property | Type | Description |
|---|---|---|
| skipRedirectCheck(optional) | boolean | Attempt to close the window without checking to see if the auth redirect matches the cached redirect URL. |
| Property | Type | Description |
|---|---|---|
| message | string | Additional description or reasoning of the result. |
| type | 'success' | 'failed' | Type of the result. |
| Property | Type | Description |
|---|---|---|
| browserPackages | string[] | All packages recognized by |
| defaultBrowserPackage(optional) | string | Default package chosen by user, |
| preferredBrowserPackage(optional) | string | Package preferred by |
| servicePackages | string[] | All packages recognized by |
| Property | Type | Description |
|---|---|---|
| browserPackage(optional) | string | Only for: Android Package name of a browser to be used to handle Custom Tabs. List of
available packages is to be queried by |
| controlsColor(optional) | string | Only for: iOS Tint color for controls in SKSafariViewController. Supports React Native color formats. |
| createTask(optional) | boolean | Only for: Android A boolean determining whether the browser should open in a new task or in the same task as your app. Default: true |
| dismissButtonStyle(optional) | 'done' | 'close' | 'cancel' | Only for: iOS The style of the dismiss button. Should be one of: |
| enableBarCollapsing(optional) | boolean | A boolean determining whether the toolbar should be hiding when a user scrolls the website. |
| enableDefaultShareMenuItem(optional) | boolean | Only for: Android A boolean determining whether a default share item should be added to the menu. |
| presentationStyle(optional) | WebBrowserPresentationStyle | Only for: iOS The presentation style of the browser window. Default: WebBrowser.WebBrowserPresentationStyle.OverFullScreen |
| readerMode(optional) | boolean | Only for: iOS A boolean determining whether Safari should enter Reader mode, if it is available. |
| secondaryToolbarColor(optional) | string | Only for: Android Color of the secondary toolbar. Supports React Native color formats. |
| showInRecents(optional) | boolean | Only for: Android A boolean determining whether browsed website should be shown as separate
entry in Android recents/multitasking view. Requires Default: false |
| showTitle(optional) | boolean | Only for: Android A boolean determining whether the browser should show the title of website on the toolbar. |
| toolbarColor(optional) | string | Color of the toolbar. Supports React Native color formats. |
| windowFeatures(optional) | string | WebBrowserWindowFeatures | Only for: Web Features to use with |
| windowName(optional) | string | Only for: Web Name to assign to the popup window. |
| Property | Type | Description |
|---|---|---|
| type | 'success' | Type of the result. |
| url | string | - |
| Property | Type | Description |
|---|---|---|
| type | WebBrowserResultType | Type of the result. |
Enums
A browser presentation style. Its values are directly mapped to the UIModalPresentationStyle.
WebBrowserPresentationStyle.AUTOMATIC ＝ "automatic"The default presentation style chosen by the system.
On older iOS versions, falls back to WebBrowserPresentationStyle.FullScreen.
WebBrowserPresentationStyle.CURRENT_CONTEXT ＝ "currentContext"A presentation style where the browser is displayed over the app's content.
WebBrowserPresentationStyle.FORM_SHEET ＝ "formSheet"A presentation style that displays the browser centered in the screen.
WebBrowserPresentationStyle.FULL_SCREEN ＝ "fullScreen"A presentation style in which the presented browser covers the screen.
WebBrowserPresentationStyle.OVER_CURRENT_CONTEXT ＝ "overCurrentContext"A presentation style where the browser is displayed over the app's content.
WebBrowserPresentationStyle.OVER_FULL_SCREEN ＝ "overFullScreen"A presentation style in which the browser view covers the screen.
WebBrowserPresentationStyle.PAGE_SHEET ＝ "pageSheet"A presentation style that partially covers the underlying content.
Error codes
ERR_WEB_BROWSER_REDIRECT
Web only: The window cannot complete the redirect request because the invoking window doesn't have a reference to its parent. This can happen if the parent window was reloaded.
ERR_WEB_BROWSER_BLOCKED
Web only: The popup window was blocked by the browser or failed to open. This can happen in mobile browsers when the window.open() method was invoked too long after a user input was fired.
Mobile browsers do this to prevent malicious websites from opening many unwanted popups on mobile.
You're method can still run in an async function but there cannot be any long running tasks before it. You can use hooks to disable user-inputs until any other processes have finished loading.
ERR_WEB_BROWSER_CRYPTO
Web only: The current environment doesn't support crypto. Ensure you are running from a secure origin (localhost/https).