electron/docs/api/webview-tag.md

<webview> Tag

Warning

Electron's webview tag is based on Chromium's webview, which is undergoing dramatic architectural changes. This impacts the stability of webviews, including rendering, navigation, and event routing. We currently recommend to not use the webview tag and to consider alternatives, like iframe, Electron's BrowserView, or an architecture that avoids embedded content altogether.

Enabling

By default the webview tag is disabled in Electron >= 5. You need to enable the tag by setting the webviewTag webPreferences option when constructing your BrowserWindow. For more information see the BrowserWindow constructor docs.

Overview

Display external web content in an isolated frame and process.

Process: Renderer

Use the webview tag to embed 'guest' content (such as web pages) in your Electron app. The guest content is contained within the webview container. An embedded page within your app controls how the guest content is laid out and rendered.

Unlike an iframe, the webview runs in a separate process than your app. It doesn't have the same permissions as your web page and all interactions between your app and embedded content will be asynchronous. This keeps your app safe from the embedded content. Note: Most methods called on the webview from the host page require a synchronous call to the main process.

Example

To embed a web page in your app, add the webview tag to your app's embedder page (this is the app page that will display the guest content). In its simplest form, the webview tag includes the src of the web page and css styles that control the appearance of the webview container:

<webview id="foo" src="https://www.github.com/" style="display:inline-flex; width:640px; height:480px"></webview>

If you want to control the guest content in any way, you can write JavaScript that listens for webview events and responds to those events using the webview methods. Here's sample code with two event listeners: one that listens for the web page to start loading, the other for the web page to stop loading, and displays a "loading..." message during the load time:

<script>
  onload = () => {
    const webview = document.querySelector('webview')
    const indicator = document.querySelector('.indicator')

    const loadstart = () => {
      indicator.innerText = 'loading...'
    }

    const loadstop = () => {
      indicator.innerText = ''
    }

    webview.addEventListener('did-start-loading', loadstart)
    webview.addEventListener('did-stop-loading', loadstop)
  }
</script>

Internal implementation

Under the hood webview is implemented with Out-of-Process iframes (OOPIFs). The webview tag is essentially a custom element using shadow DOM to wrap an iframe element inside it.

So the behavior of webview is very similar to a cross-domain iframe, as examples:

• When clicking into a webview, the page focus will move from the embedder frame to webview.
• You can not add keyboard, mouse, and scroll event listeners to webview.
• All reactions between the embedder frame and webview are asynchronous.

CSS Styling Notes

Please note that the webview tag's style uses display:flex; internally to ensure the child iframe element fills the full height and width of its webview container when used with traditional and flexbox layouts. Please do not overwrite the default display:flex; CSS property, unless specifying display:inline-flex; for inline layout.

Tag Attributes

The webview tag has the following attributes:

src

<webview src="https://www.github.com/"></webview>

A String representing the visible URL. Writing to this attribute initiates top-level navigation.

Assigning src its own value will reload the current page.

The src attribute can also accept data URLs, such as data:text/plain,Hello, world!.

nodeintegration

<webview src="http://www.google.com/" nodeintegration></webview>

A Boolean. When this attribute is present the guest page in webview will have node integration and can use node APIs like require and process to access low level system resources. Node integration is disabled by default in the guest page.

nodeintegrationinsubframes

<webview src="http://www.google.com/" nodeintegrationinsubframes></webview>

A Boolean for the experimental option for enabling NodeJS support in sub-frames such as iframes inside the webview. All your preloads will load for every iframe, you can use process.isMainFrame to determine if you are in the main frame or not. This option is disabled by default in the guest page.

plugins

<webview src="https://www.github.com/" plugins></webview>

A Boolean. When this attribute is present the guest page in webview will be able to use browser plugins. Plugins are disabled by default.

preload

<webview src="https://www.github.com/" preload="./test.js"></webview>

A String that specifies a script that will be loaded before other scripts run in the guest page. The protocol of script's URL must be either file: or asar:, because it will be loaded by require in guest page under the hood.

When the guest page doesn't have node integration this script will still have access to all Node APIs, but global objects injected by Node will be deleted after this script has finished executing.

Note: This option will appear as preloadURL (not preload) in the webPreferences specified to the will-attach-webview event.

httpreferrer

<webview src="https://www.github.com/" httpreferrer="http://cheng.guru"></webview>

A String that sets the referrer URL for the guest page.

useragent

<webview src="https://www.github.com/" useragent="Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; AS; rv:11.0) like Gecko"></webview>

A String that sets the user agent for the guest page before the page is navigated to. Once the page is loaded, use the setUserAgent method to change the user agent.

disablewebsecurity

<webview src="https://www.github.com/" disablewebsecurity></webview>

A Boolean. When this attribute is present the guest page will have web security disabled. Web security is enabled by default.

partition

<webview src="https://github.com" partition="persist:github"></webview>
<webview src="https://electronjs.org" partition="electron"></webview>

A String that sets the session used by the page. If partition starts with persist:, the page will use a persistent session available to all pages in the app with the same partition. if there is no persist: prefix, the page will use an in-memory session. By assigning the same partition, multiple pages can share the same session. If the partition is unset then default session of the app will be used.

This value can only be modified before the first navigation, since the session of an active renderer process cannot change. Subsequent attempts to modify the value will fail with a DOM exception.

allowpopups

<webview src="https://www.github.com/" allowpopups></webview>

A Boolean. When this attribute is present the guest page will be allowed to open new windows. Popups are disabled by default.

webpreferences

<webview src="https://github.com" webpreferences="allowRunningInsecureContent, javascript=no"></webview>

A String which is a comma separated list of strings which specifies the web preferences to be set on the webview. The full list of supported preference strings can be found in BrowserWindow.

The string follows the same format as the features string in window.open. A name by itself is given a true boolean value. A preference can be set to another value by including an =, followed by the value. Special values yes and 1 are interpreted as true, while no and 0 are interpreted as false.

enableblinkfeatures

<webview src="https://www.github.com/" enableblinkfeatures="PreciseMemoryInfo, CSSVariables"></webview>

A String which is a list of strings which specifies the blink features to be enabled separated by ,. The full list of supported feature strings can be found in the RuntimeEnabledFeatures.json5 file.

disableblinkfeatures

<webview src="https://www.github.com/" disableblinkfeatures="PreciseMemoryInfo, CSSVariables"></webview>

A String which is a list of strings which specifies the blink features to be disabled separated by ,. The full list of supported feature strings can be found in the RuntimeEnabledFeatures.json5 file.

Methods

The webview tag has the following methods:

Note: The webview element must be loaded before using the methods.

Example

const webview = document.querySelector('webview')
webview.addEventListener('dom-ready', () => {
  webview.openDevTools()
})

<webview>.loadURL(url[, options])

• url URL
• options Object (optional)
  • httpReferrer (String | Referrer) (optional) - An HTTP Referrer url.
  • userAgent String (optional) - A user agent originating the request.
  • extraHeaders String (optional) - Extra headers separated by "\n"
  • postData (UploadRawData | UploadFile)[] (optional)
  • baseURLForDataURL String (optional) - Base url (with trailing path separator) for files to be loaded by the data url. This is needed only if the specified url is a data url and needs to load other files.

Returns Promise<void> - The promise will resolve when the page has finished loading (see did-finish-load), and rejects if the page fails to load (see did-fail-load).

Loads the url in the webview, the url must contain the protocol prefix, e.g. the http:// or file://.

<webview>.downloadURL(url)

• url String

Initiates a download of the resource at url without navigating.

<webview>.getURL()

Returns String - The URL of guest page.

<webview>.getTitle()

Returns String - The title of guest page.

<webview>.isLoading()

Returns Boolean - Whether guest page is still loading resources.

<webview>.isLoadingMainFrame()

Returns Boolean - Whether the main frame (and not just iframes or frames within it) is still loading.

<webview>.isWaitingForResponse()

Returns Boolean - Whether the guest page is waiting for a first-response for the main resource of the page.

<webview>.stop()

Stops any pending navigation.

<webview>.reload()

Reloads the guest page.

<webview>.reloadIgnoringCache()

Reloads the guest page and ignores cache.

<webview>.canGoBack()

Returns Boolean - Whether the guest page can go back.

<webview>.canGoForward()

Returns Boolean - Whether the guest page can go forward.

<webview>.canGoToOffset(offset)

• offset Integer

Returns Boolean - Whether the guest page can go to offset.

<webview>.clearHistory()

Clears the navigation history.

<webview>.goBack()

Makes the guest page go back.

<webview>.goForward()

Makes the guest page go forward.

<webview>.goToIndex(index)

• index Integer

Navigates to the specified absolute index.

<webview>.goToOffset(offset)

• offset Integer

Navigates to the specified offset from the "current entry".

<webview>.isCrashed()

Returns Boolean - Whether the renderer process has crashed.

<webview>.setUserAgent(userAgent)

• userAgent String

Overrides the user agent for the guest page.

<webview>.getUserAgent()

Returns String - The user agent for guest page.

<webview>.insertCSS(css)

• css String

Returns Promise<String> - A promise that resolves with a key for the inserted CSS that can later be used to remove the CSS via <webview>.removeInsertedCSS(key).

Injects CSS into the current web page and returns a unique key for the inserted stylesheet.

<webview>.removeInsertedCSS(key)

• key String

Returns Promise<void> - Resolves if the removal was successful.

Removes the inserted CSS from the current web page. The stylesheet is identified by its key, which is returned from <webview>.insertCSS(css).

<webview>.executeJavaScript(code[, userGesture])

• code String
• userGesture Boolean (optional) - Default false.

Returns Promise<any> - A promise that resolves with the result of the executed code or is rejected if the result of the code is a rejected promise.

Evaluates code in page. If userGesture is set, it will create the user gesture context in the page. HTML APIs like requestFullScreen, which require user action, can take advantage of this option for automation.

<webview>.openDevTools()

Opens a DevTools window for guest page.

<webview>.closeDevTools()

Closes the DevTools window of guest page.

<webview>.isDevToolsOpened()

Returns Boolean - Whether guest page has a DevTools window attached.

<webview>.isDevToolsFocused()

Returns Boolean - Whether DevTools window of guest page is focused.

<webview>.inspectElement(x, y)

• x Integer
• y Integer

Starts inspecting element at position (x, y) of guest page.

<webview>.inspectSharedWorker()

Opens the DevTools for the shared worker context present in the guest page.

<webview>.inspectServiceWorker()

Opens the DevTools for the service worker context present in the guest page.

<webview>.setAudioMuted(muted)

• muted Boolean

Set guest page muted.

<webview>.isAudioMuted()

Returns Boolean - Whether guest page has been muted.

<webview>.isCurrentlyAudible()

Returns Boolean - Whether audio is currently playing.

<webview>.undo()

Executes editing command undo in page.

<webview>.redo()

Executes editing command redo in page.

<webview>.cut()

Executes editing command cut in page.

<webview>.copy()

Executes editing command copy in page.

<webview>.paste()

Executes editing command paste in page.

<webview>.pasteAndMatchStyle()

Executes editing command pasteAndMatchStyle in page.

<webview>.delete()

Executes editing command delete in page.

<webview>.selectAll()

Executes editing command selectAll in page.

<webview>.unselect()

Executes editing command unselect in page.

<webview>.replace(text)

• text String

Executes editing command replace in page.

<webview>.replaceMisspelling(text)

• text String

Executes editing command replaceMisspelling in page.

<webview>.insertText(text)

• text String

Returns Promise<void>

Inserts text to the focused element.

<webview>.findInPage(text[, options])

• text String - Content to be searched, must not be empty.
• options Object (optional)
  • forward Boolean (optional) - Whether to search forward or backward, defaults to true.
  • findNext Boolean (optional) - Whether the operation is first request or a follow up, defaults to false.
  • matchCase Boolean (optional) - Whether search should be case-sensitive, defaults to false.

Returns Integer - The request id used for the request.

Starts a request to find all matches for the text in the web page. The result of the request can be obtained by subscribing to found-in-page event.

<webview>.stopFindInPage(action)

• action String - Specifies the action to take place when ending <webview>.findInPage request.
  • clearSelection - Clear the selection.
  • keepSelection - Translate the selection into a normal selection.
  • activateSelection - Focus and click the selection node.

Stops any findInPage request for the webview with the provided action.

<webview>.print([options])

• options Object (optional)
  • silent Boolean (optional) - Don't ask user for print settings. Default is false.
  • printBackground Boolean (optional) - Prints the background color and image of the web page. Default is false.
  • deviceName String (optional) - Set the printer device name to use. Must be the system-defined name and not the 'friendly' name, e.g 'Brother_QL_820NWB' and not 'Brother QL-820NWB'.
  • color Boolean (optional) - Set whether the printed web page will be in color or grayscale. Default is true.
  • margins Object (optional)
    • marginType String (optional) - Can be default, none, printableArea, or custom. If custom is chosen, you will also need to specify top, bottom, left, and right.
    • top Number (optional) - The top margin of the printed web page, in pixels.
    • bottom Number (optional) - The bottom margin of the printed web page, in pixels.
    • left Number (optional) - The left margin of the printed web page, in pixels.
    • right Number (optional) - The right margin of the printed web page, in pixels.
  • landscape Boolean (optional) - Whether the web page should be printed in landscape mode. Default is false.
  • scaleFactor Number (optional) - The scale factor of the web page.
  • pagesPerSheet Number (optional) - The number of pages to print per page sheet.
  • collate Boolean (optional) - Whether the web page should be collated.
  • copies Number (optional) - The number of copies of the web page to print.
  • pageRanges Object[] (optional) - The page range to print.
    • from Number - Index of the first page to print (0-based).
    • to Number - Index of the last page to print (inclusive) (0-based).
  • duplexMode String (optional) - Set the duplex mode of the printed web page. Can be simplex, shortEdge, or longEdge.
  • dpi Record<string, number> (optional)
    • horizontal Number (optional) - The horizontal dpi.
    • vertical Number (optional) - The vertical dpi.
  • header String (optional) - String to be printed as page header.
  • footer String (optional) - String to be printed as page footer.
  • pageSize String | Size (optional) - Specify page size of the printed document. Can be A3, A4, A5, Legal, Letter, Tabloid or an Object containing height.

Returns Promise<void>

Prints webview's web page. Same as webContents.print([options]).

<webview>.printToPDF(options)

• options Object
  • headerFooter Record<string, string> (optional) - the header and footer for the PDF.
    • title String - The title for the PDF header.
    • url String - the url for the PDF footer.
  • landscape Boolean (optional) - true for landscape, false for portrait.
  • marginsType Integer (optional) - Specifies the type of margins to use. Uses 0 for default margin, 1 for no margin, and 2 for minimum margin. and width in microns.
  • scaleFactor Number (optional) - The scale factor of the web page. Can range from 0 to 100.
  • pageRanges Record<string, number> (optional) - The page range to print. On macOS, only the first range is honored.
    • from Number - Index of the first page to print (0-based).
    • to Number - Index of the last page to print (inclusive) (0-based).
  • pageSize String | Size (optional) - Specify page size of the generated PDF. Can be A3, A4, A5, Legal, Letter, Tabloid or an Object containing height
  • printBackground Boolean (optional) - Whether to print CSS backgrounds.
  • printSelectionOnly Boolean (optional) - Whether to print selection only.

Returns Promise<Uint8Array> - Resolves with the generated PDF data.

Prints webview's web page as PDF, Same as webContents.printToPDF(options).

<webview>.capturePage([rect])

• rect Rectangle (optional) - The area of the page to be captured.

Returns Promise<NativeImage> - Resolves with a NativeImage

Captures a snapshot of the page within rect. Omitting rect will capture the whole visible page.

<webview>.send(channel, ...args)

• channel String
• ...args any[]

Returns Promise<void>

Send an asynchronous message to renderer process via channel, you can also send arbitrary arguments. The renderer process can handle the message by listening to the channel event with the ipcRenderer module.

See webContents.send for examples.

<webview>.sendInputEvent(event)

• event MouseInputEvent | MouseWheelInputEvent | KeyboardInputEvent

Returns Promise<void>

Sends an input event to the page.

See webContents.sendInputEvent for detailed description of event object.

<webview>.setZoomFactor(factor)

• factor Number - Zoom factor.

Changes the zoom factor to the specified factor. Zoom factor is zoom percent divided by 100, so 300% = 3.0.

<webview>.setZoomLevel(level)

• level Number - Zoom level.

Changes the zoom level to the specified level. The original size is 0 and each increment above or below represents zooming 20% larger or smaller to default limits of 300% and 50% of original size, respectively. The formula for this is scale := 1.2 ^ level.

Note

: The zoom policy at the Chromium level is same-origin, meaning that the zoom level for a specific domain propagates across all instances of windows with the same domain. Differentiating the window URLs will make zoom work per-window.

<webview>.getZoomFactor()

Returns Number - the current zoom factor.

<webview>.getZoomLevel()

Returns Number - the current zoom level.

<webview>.setVisualZoomLevelLimits(minimumLevel, maximumLevel)

• minimumLevel Number
• maximumLevel Number

Returns Promise<void>

Sets the maximum and minimum pinch-to-zoom level.

<webview>.showDefinitionForSelection() macOS

Shows pop-up dictionary that searches the selected word on the page.

<webview>.getWebContentsId()

Returns Number - The WebContents ID of this webview.

DOM Events

The following DOM events are available to the webview tag:

Event: 'load-commit'

Returns:

• url String
• isMainFrame Boolean

Fired when a load has committed. This includes navigation within the current document as well as subframe document-level loads, but does not include asynchronous resource loads.

Event: 'did-finish-load'

Fired when the navigation is done, i.e. the spinner of the tab will stop spinning, and the onload event is dispatched.

Event: 'did-fail-load'

Returns:

• errorCode Integer
• errorDescription String
• validatedURL String
• isMainFrame Boolean

This event is like did-finish-load, but fired when the load failed or was cancelled, e.g. window.stop() is invoked.

Event: 'did-frame-finish-load'

Returns:

• isMainFrame Boolean

Fired when a frame has done navigation.

Event: 'did-start-loading'

Corresponds to the points in time when the spinner of the tab starts spinning.

Event: 'did-stop-loading'

Corresponds to the points in time when the spinner of the tab stops spinning.

Event: 'dom-ready'

Fired when document in the given frame is loaded.

Event: 'page-title-updated'

Returns:

• title String
• explicitSet Boolean

Fired when page title is set during navigation. explicitSet is false when title is synthesized from file url.

Event: 'page-favicon-updated'

Returns:

• favicons String[] - Array of URLs.

Fired when page receives favicon urls.

Event: 'enter-html-full-screen'

Fired when page enters fullscreen triggered by HTML API.

Event: 'leave-html-full-screen'

Fired when page leaves fullscreen triggered by HTML API.

Event: 'console-message'

Returns:

• level Integer - The log level, from 0 to 3. In order it matches verbose, info, warning and error.
• message String - The actual console message
• line Integer - The line number of the source that triggered this console message
• sourceId String

Fired when the guest window logs a console message.

The following example code forwards all log messages to the embedder's console without regard for log level or other properties.

const webview = document.querySelector('webview')
webview.addEventListener('console-message', (e) => {
  console.log('Guest page logged a message:', e.message)
})

Event: 'found-in-page'

Returns:

• result Object
  • requestId Integer
  • activeMatchOrdinal Integer - Position of the active match.
  • matches Integer - Number of Matches.
  • selectionArea Rectangle - Coordinates of first match region.
  • finalUpdate Boolean

Fired when a result is available for webview.findInPage request.

const webview = document.querySelector('webview')
webview.addEventListener('found-in-page', (e) => {
  webview.stopFindInPage('keepSelection')
})

const requestId = webview.findInPage('test')
console.log(requestId)

Event: 'new-window'

Returns:

• url String
• frameName String
• disposition String - Can be default, foreground-tab, background-tab, new-window, save-to-disk and other.
• options BrowserWindowConstructorOptions - The options which should be used for creating the new BrowserWindow.

Fired when the guest page attempts to open a new browser window.

The following example code opens the new url in system's default browser.

const { shell } = require('electron')
const webview = document.querySelector('webview')

webview.addEventListener('new-window', async (e) => {
  const protocol = (new URL(e.url)).protocol
  if (protocol === 'http:' || protocol === 'https:') {
    await shell.openExternal(e.url)
  }
})

Event: 'will-navigate'

Returns:

• url String

Emitted when a user or the page wants to start navigation. It can happen when the window.location object is changed or a user clicks a link in the page.

This event will not emit when the navigation is started programmatically with APIs like <webview>.loadURL and <webview>.back.

It is also not emitted during in-page navigation, such as clicking anchor links or updating the window.location.hash. Use did-navigate-in-page event for this purpose.

Calling event.preventDefault() does NOT have any effect.

Event: 'did-navigate'

Returns:

• url String

Emitted when a navigation is done.

This event is not emitted for in-page navigations, such as clicking anchor links or updating the window.location.hash. Use did-navigate-in-page event for this purpose.

Event: 'did-navigate-in-page'

Returns:

• isMainFrame Boolean
• url String

Emitted when an in-page navigation happened.

When in-page navigation happens, the page URL changes but does not cause navigation outside of the page. Examples of this occurring are when anchor links are clicked or when the DOM hashchange event is triggered.

Event: 'close'

Fired when the guest page attempts to close itself.

The following example code navigates the webview to about:blank when the guest attempts to close itself.

const webview = document.querySelector('webview')
webview.addEventListener('close', () => {
  webview.src = 'about:blank'
})

Event: 'ipc-message'

Returns:

• channel String
• args any[]

Fired when the guest page has sent an asynchronous message to embedder page.

With sendToHost method and ipc-message event you can communicate between guest page and embedder page:

// In embedder page.
const webview = document.querySelector('webview')
webview.addEventListener('ipc-message', (event) => {
  console.log(event.channel)
  // Prints "pong"
})
webview.send('ping')

// In guest page.
const { ipcRenderer } = require('electron')
ipcRenderer.on('ping', () => {
  ipcRenderer.sendToHost('pong')
})

Event: 'crashed'

Fired when the renderer process is crashed.

Event: 'plugin-crashed'

Returns:

• name String
• version String

Fired when a plugin process is crashed.

Event: 'destroyed'

Fired when the WebContents is destroyed.

Event: 'media-started-playing'

Emitted when media starts playing.

Event: 'media-paused'

Emitted when media is paused or done playing.

Event: 'did-change-theme-color'

Returns:

• themeColor String

Emitted when a page's theme color changes. This is usually due to encountering a meta tag:

<meta name='theme-color' content='#ff0000'>

Event: 'update-target-url'

Returns:

• url String

Emitted when mouse moves over a link or the keyboard moves the focus to a link.

Event: 'devtools-opened'

Emitted when DevTools is opened.

Event: 'devtools-closed'

Emitted when DevTools is closed.

Event: 'devtools-focused'

Emitted when DevTools is focused / opened.