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Expo WebBrowser

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A 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 SFAuthenticationSession, 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.

Platform Compatibility

Android Device	Android Emulator	iOS Device	iOS Simulator	Web

Installation

Terminal

- npx expo install expo-web-browser

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

Usage

Basic WebBrowser usage

import React, { 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>
  );
}

%%placeholder-start%%const styles = StyleSheet.create({ ... }); %%placeholder-end%%const styles = StyleSheet.create({
  container: {
    flex: 1,
    alignItems: 'center',
    justifyContent: 'center',
    paddingTop: Constants.statusBarHeight,
    backgroundColor: '#ecf0f1',
  },
});

Handling deep links from the WebBrowser

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

Only for:

Android

`WebBrowser.coolDownAsync(browserPackage)`

Name	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.

Returns

Promise<WebBrowserCoolDownResult>

The promise which fulfils with WebBrowserCoolDownResult when cooling is performed, or an empty object when there was no connection to be dismissed.

`WebBrowser.dismissAuthSession()`

Returns

void

Only for:

iOS

`WebBrowser.dismissBrowser()`

Dismisses the presented web browser.

Returns

void

The void on successful attempt, or throws error, if dismiss functionality is not avaiable.

Only for:

Android

`WebBrowser.getCustomTabsSupportingBrowsersAsync()`

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.)

Returns

Promise<WebBrowserCustomTabsResults>

The promise which fulfils with WebBrowserCustomTabsResults object.

Only for:

Android

`WebBrowser.mayInitWithUrlAsync(url, browserPackage)`

Name	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.

Returns

Promise<WebBrowserMayInitWithUrlResult>

A promise which fulfils with WebBrowserMayInitWithUrlResult object.

Only for:

Web

`WebBrowser.maybeCompleteAuthSession(options)`

Name	Type	Description
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

WebBrowserCompleteAuthSessionResult

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 (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.

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.

`WebBrowser.openAuthSessionAsync(url, redirectUrl, options)`

Name	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 `Linking.createURL("")`.
options (optional)	`AuthSessionOpenOptions`	Optional - An object extending the `WebBrowserOpenOptions`. 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. Default: `{}`

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.

Returns

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.

`WebBrowser.openBrowserAsync(url, browserParams)`

Name	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.

Returns

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' }.

Only for:

Android

`WebBrowser.warmUpAsync(browserPackage)`

Name	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.

Returns

Promise<WebBrowserWarmUpResult>

A promise which fulfils with WebBrowserWarmUpResult object.

Types

`AuthSessionOpenOptions`

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.

WebBrowserOpenOptions extended by:

Name	Type	Description
preferEphemeralSession (optional)	`boolean`	Only for: iOS 13+ Determines whether the session should ask the browser for a private authentication session. Set this to `true` to request that the browser doesn’t share cookies or other browsing data between the authentication session and the user’s normal browser session. Whether the request is honored depends on the user’s default web browser. Default: `false`

`WebBrowserAuthSessionResult`

Acceptable values are: WebBrowserRedirectResult, WebBrowserResult.

`WebBrowserCompleteAuthSessionOptions`

Name	Type	Description
skipRedirectCheck (optional)	`boolean`	Attempt to close the window without checking to see if the auth redirect matches the cached redirect URL.

`WebBrowserCompleteAuthSessionResult`

Name	Type	Description
message	`string`	Additional description or reasoning of the result.
type	`'success' \| 'failed'`	Type of the result.

`WebBrowserCoolDownResult`

Type: ServiceActionResult

`WebBrowserCustomTabsResults`

Name	Type	Description
browserPackages	`string[]`	All packages recognized by `PackageManager` as capable of handling Custom Tabs. Empty array means there is no supporting browsers on device.
defaultBrowserPackage (optional)	`string`	Default package chosen by user, `null` if there is no such packages. Also `null` usually means, that user will be prompted to choose from available packages.
preferredBrowserPackage (optional)	`string`	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.
servicePackages	`string[]`	All packages recognized by `PackageManager` as capable of handling Custom Tabs Service. This service is used by `warmUpAsync`, `mayInitWithUrlAsync` and `coolDownAsync`.

`WebBrowserMayInitWithUrlResult`

Type: ServiceActionResult

`WebBrowserOpenOptions`

Name	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 `getCustomTabsSupportingBrowsers` method.
controlsColor (optional)	`string`	Only for: iOS Tint color for controls in SKSafariViewController in `#AARRGGBB` or `#RRGGBB` format.
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: `done`, `close`, or `cancel`.
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 in either `#AARRGGBB` or `#RRGGBB` format.
showInRecents (optional)	`boolean`	Only for: Android A boolean determining whether browsed website should be shown as separate entry in Android recents/multitasking view. Requires `createTask` to be `true` (default). 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 in either `#AARRGGBB` or `#RRGGBB` format.
windowFeatures (optional)	`string \| WebBrowserWindowFeatures`	Only for: Web Features to use with `window.open()`.
windowName (optional)	`string`	Only for: Web Name to assign to the popup window.

`WebBrowserRedirectResult`

Name	Type	Description
type	`'success'`	Type of the result.
url	`string`	-

`WebBrowserResult`

Name	Type	Description
type	`WebBrowserResultType`	Type of the result.

`WebBrowserWarmUpResult`

Type: ServiceActionResult

`WebBrowserWindowFeatures`

Type: Record<string, number | boolean | string>

Enums

Only for:

iOS

`WebBrowserPresentationStyle`

A browser presentation style. Its values are directly mapped to the UIModalPresentationStyle.

WebBrowserPresentationStyle Values

Only for:

iOS 13+

`AUTOMATIC`

WebBrowserPresentationStyle.AUTOMATIC ＝ "automatic"

The default presentation style chosen by the system. On older iOS versions, falls back to WebBrowserPresentationStyle.FullScreen.

`CURRENT_CONTEXT`

WebBrowserPresentationStyle.CURRENT_CONTEXT ＝ "currentContext"

A presentation style where the browser is displayed over the app's content.

`FORM_SHEET`

WebBrowserPresentationStyle.FORM_SHEET ＝ "formSheet"

A presentation style that displays the browser centered in the screen.

`FULL_SCREEN`

WebBrowserPresentationStyle.FULL_SCREEN ＝ "fullScreen"

A presentation style in which the presented browser covers the screen.

`OVER_CURRENT_CONTEXT`

WebBrowserPresentationStyle.OVER_CURRENT_CONTEXT ＝ "overCurrentContext"

A presentation style where the browser is displayed over the app's content.

`OVER_FULL_SCREEN`

WebBrowserPresentationStyle.OVER_FULL_SCREEN ＝ "overFullScreen"

A presentation style in which the browser view covers the screen.

`PAGE_SHEET`

WebBrowserPresentationStyle.PAGE_SHEET ＝ "pageSheet"

A presentation style that partially covers the underlying content.

`POPOVER`

WebBrowserPresentationStyle.POPOVER ＝ "popover"

A presentation style where the browser is displayed in a popover view.

`WebBrowserResultType`

WebBrowserResultType Values

Only for:

iOS

`CANCEL`

WebBrowserResultType.CANCEL ＝ "cancel"

Only for:

iOS

`DISMISS`

WebBrowserResultType.DISMISS ＝ "dismiss"

`LOCKED`

WebBrowserResultType.LOCKED ＝ "locked"

Only for:

Android

`OPENED`

WebBrowserResultType.OPENED ＝ "opened"

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 it's 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 (https).

Tip: You can run npx expo start --web --https to open your web page in a secure development environment.

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Expo WebBrowser