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API Reference

WebBrowser

expo-web-browser provides access to the system's web browser and supports handling redirects. On iOS, it uses SFSafariViewController or SFAuthenticationSession, depending on the method you call, and on Android it uses ChromeCustomTabs. As of iOS 11, SFSafariViewController no longer shares cookies with the 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.

Platform Compatibility

Android DeviceAndroid EmulatoriOS DeviceiOS SimulatorWeb

Installation

expo install expo-web-browser

If you're installing this in a bare React Native app, you should also follow these additional installation instructions.

import React, { Component } from 'react';
import { Button, Text, View } from 'react-native';
import * as WebBrowser from 'expo-web-browser';

export default class App extends Component {
  state = {
    result: null,
  };

  render() {
    return (
      <View>
        <Button title="Open WebBrowser" onPress={this._handlePressButtonAsync} />
        <Text>{this.state.result && JSON.stringify(this.state.result)}</Text>
      </View>
    );
  }

  _handlePressButtonAsync = async () => {
    let result = await WebBrowser.openBrowserAsync('https://expo.io');
    this.setState({ result });
  };
}

If you are using the WebBrowser window for authentication or another use case where you would like to pass information back into your app through a deep link, be sure to add a handler with Linking.addEventListener before opening the browser. When the listener fires, you should call dismissBrowser -- it will not automatically dismiss when a deep link is handled. Aside from that, redirects from WebBrowser work the same as other deep links. Read more about it in the Linking guide.

import * as WebBrowser from 'expo-web-browser';

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.

  • url (string) -- The url to open in the web browser.
  • browserParams (object) (optional) -- A dictionary with following key-value pairs:
    • controlsColor (optional) (string) -- (iOS only) tint color for controls in SKSafariViewController in #AARRGGBB or #RRGGBB format.
    • dismissButtonStyle (optional) (string) -- (iOS only) The style of the dismiss button. Should be one of: done, close, or cancel.
    • enableBarCollapsing (optional) (boolean) -- a boolean determining whether the toolbar should be hiding when a user scrolls the website.
    • enableDefaultShare (optional) (boolean) -- (Android only) a boolean determining whether a default share item should be added to the menu.
    • package (optional) (string) -- (Android only). Package name of a browser to be used to handle Custom Tabs. List of available packages is to be queried by getCustomTabsSupportingBrowsers method.
    • readerMode (optional) (boolean) -- (iOS only) a boolean determining whether Safari should enter Reader mode, if it is available.
    • showInRecents (optional) (boolean) -- (Android only) a boolean determining whether browsed website should be shown as separate entry in Android recents/multitasking view. Default: false
    • showTitle (optional) (boolean) -- (Android only) a boolean determining whether the browser should show the title of website on the toolbar.
    • toolbarColor (optional) (string) -- color of the toolbar in either #AARRGGBB or #RRGGBB format.
    Note that behavior customization options depend on the actual browser and its version. Some or all of the arguments may be ignored.

The promise behaves differently on iOS and Android.
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' }.

On iOS:
Opens the url with Safari in a modal using SFAuthenticationSession on iOS 11 and greater, and falling back on a SFSafariViewController. The user will be asked whether to allow the app to authenticate using the given url.
On Android:
This will be done using a "custom Chrome tabs" browser, AppState, and Linking APIs.
On web:
🚨
This API can only be used in a secure environment (https). You can use expo start:web --https to test this. Otherwise an error with code ERR_WEB_BROWSER_CRYPTO will be thrown.
This will use the browser's window.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 expo start:web --https.
  • 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: if openAuthSessionAsync is invoked on https://localhost:19006, then maybeCompleteAuthSession must be invoked on a page hosted from the origin https://localhost:19006. Using a different website, or even a different host like https://128.0.0.*:19006 for 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 code ERR_WEB_BROWSER_BLOCKED will be thrown.

  • url (string) -- The url to open in the web browser. This should be a login page.
  • redirectUrl (string) -- optional: the url to deep link back into your app. By default, this will be Constants.linkingUrl
  • browserParams (object) -- optional: an object with the same keys as openBrowserAsync's browserParams object. If there is no native AuthSession implementation available (which is the case on Android) these params will be used in the browser polyfill. If there is a native AuthSession implementation, these params will be ignored.
Returns a Promise:
  • If the user does not permit the application to authenticate with the given url, the Promise resolved with { type: 'cancel' }.
  • 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' }.

Web Only: Possibly completes an authentication session on web in a window popup. The method should be invoked on the page that the window redirects to.

  • skipRedirectCheck (boolean) -- optional: Attempt to close the window without checking to see if the auth redirect matches the cached redirect URL.
Returns a message about why the redirect failed or succeeded:
  • { type: 'failed' }:
    • Not supported on this platform: If the platform doesn't support this method (iOS, Android).
    • 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 the redirectUrl and returnUrl.
    • 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 the returnUrl. You can skip this test in development by passing { skipRedirectCheck: true } to the function.
  • { type: '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.

Android only
This method calls warmUp method on CustomTabsClient for specified package.

  • browserPackage (string) -- optional -- package of browser to be warmed up. If not set, preferred browser will be warmed.

A promise resolving with { package: string }

Android only
This method initiates (if needed) CustomTabsSession and calls its mayLaunchUrl method for browser specified by the package.

  • url (string) -- url of page that is likely to be loaded firts when opening browser
  • package (string) -- optional -- package of browser to be informed. If not set, preferred browser will be used.

The promise resolves with { package: string }.

Android only
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.

  • browserPackage (string) -- optional -- package of browser to be cooled. If not set, preferred browser will be used.

The promise resolves with { package: string } when cooling is performed, or an empty object when there was no connection to be dismissed.

iOS only
Dismisses the presented web browser.

The promise resolves with { type: 'dismiss' }.

Android only
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 defult.)

The promise resolves with { browserPackages: string[], defaultBrowserPackage: string, servicePackages: string[], preferredBrowserPackage: string }
  • browserPackages (string[]) : All packages recognized by PackageManager as capable of handling Custom Tabs. Empty array means there is no supporting browsers on device.
  • defaultBrowserPackage (string | null) : Default package chosen by user. Null if there is no such packages. Null usually means, that user will be prompted to choose from available packages.
  • servicePackages (string[]) : All packages recognized by PackageManager as capable of handling Custom Tabs Service. This service is used by warmUpAsync, mayInitWithUrlAsync and coolDownAsync.
  • preferredBrowserPackage (string | null) : Package preferred by CustomTabsClient to be used to handle Custom Tabs. It favors browser chosen by user as default, as long as it is present on both browserPackages and servicePackages lists. Only such browsers are considered as fully supporting Custom Tabs. It might be null when there is no such browser installed or when default browser is not in servicePackages list.
In general, services are used to perform background tasks. If a browser is available in servicePackage list, it should be capable of performing warmUpAsync, mayInitWithUrlAsync and coolDownAsync. For opening an actual web page, browser must be in browserPackages list. A browser has to be present in both lists to be considered as fully supporting Custom Tabs.

Web only: The window cannot complete the redirect request because the invoking window doesn't have a reference to it's parent. This can happen if the parent window was reloaded.

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.

Web only: The current environment doesn't support crypto. Ensure you are running from a secure origin (https).
When using Expo CLI you can run expo start:web --https or expo start --web --https to open your web page in a secure development environment.