W3cubDocs

/Electron

webContents

Render and control web pages.

Process: Main

webContents is an EventEmitter. It is responsible for rendering and controlling a web page and is a property of the BrowserWindow object. An example of accessing the webContents object:

const { BrowserWindow } = require('electron')

const win = new BrowserWindow({ width: 800, height: 1500 })
win.loadURL('http://github.com')

const contents = win.webContents
console.log(contents)

Methods

These methods can be accessed from the webContents module:

const { webContents } = require('electron')
console.log(webContents)

webContents.getAllWebContents()

Returns WebContents[] - An array of all WebContents instances. This will contain web contents for all windows, webviews, opened devtools, and devtools extension background pages.

webContents.getFocusedWebContents()

Returns WebContents - The web contents that is focused in this application, otherwise returns null.

webContents.fromId(id)

  • id Integer

Returns WebContents - A WebContents instance with the given ID.

Class: WebContents

Render and control the contents of a BrowserWindow instance.

Process: Main

Instance Events

Event: 'did-finish-load'

Emitted when the navigation is done, i.e. the spinner of the tab has stopped spinning, and the onload event was dispatched.

Event: 'did-fail-load'

Returns:

  • event Event
  • errorCode Integer
  • errorDescription String
  • validatedURL String
  • isMainFrame Boolean
  • frameProcessId Integer
  • frameRoutingId Integer

This event is like did-finish-load but emitted when the load failed. The full list of error codes and their meaning is available here.

Event: 'did-fail-provisional-load'

Returns:

  • event Event
  • errorCode Integer
  • errorDescription String
  • validatedURL String
  • isMainFrame Boolean
  • frameProcessId Integer
  • frameRoutingId Integer

This event is like did-fail-load but emitted when the load was cancelled (e.g. window.stop() was invoked).

Event: 'did-frame-finish-load'

Returns:

  • event Event
  • isMainFrame Boolean
  • frameProcessId Integer
  • frameRoutingId Integer

Emitted when a frame has done navigation.

Event: 'did-start-loading'

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

Event: 'did-stop-loading'

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

Event: 'dom-ready'

Returns:

  • event Event

Emitted when the document in the given frame is loaded.

Event: 'page-title-updated'

Returns:

  • event Event
  • 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:

  • event Event
  • favicons String[] - Array of URLs.

Emitted when page receives favicon urls.

Event: 'new-window'

Returns:

  • event NewWindowWebContentsEvent
  • 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 will be used for creating the new BrowserWindow.
  • additionalFeatures String[] - The non-standard features (features not handled by Chromium or Electron) given to window.open().
  • referrer Referrer - The referrer that will be passed to the new window. May or may not result in the Referer header being sent, depending on the referrer policy.
  • postBody PostBody (optional) - The post data that will be sent to the new window, along with the appropriate headers that will be set. If no post data is to be sent, the value will be null. Only defined when the window is being created by a form that set target=_blank.

Emitted when the page requests to open a new window for a url. It could be requested by window.open or an external link like <a target='_blank'>.

By default a new BrowserWindow will be created for the url.

Calling event.preventDefault() will prevent Electron from automatically creating a new BrowserWindow. If you call event.preventDefault() and manually create a new BrowserWindow then you must set event.newGuest to reference the new BrowserWindow instance, failing to do so may result in unexpected behavior. For example:

myBrowserWindow.webContents.on('new-window', (event, url, frameName, disposition, options, additionalFeatures, referrer, postBody) => {
  event.preventDefault()
  const win = new BrowserWindow({
    webContents: options.webContents, // use existing webContents if provided
    show: false
  })
  win.once('ready-to-show', () => win.show())
  if (!options.webContents) {
    const loadOptions = {
      httpReferrer: referrer
    }
    if (postBody != null) {
      const { data, contentType, boundary } = postBody
      loadOptions.postData = postBody.data
      loadOptions.extraHeaders = `content-type: ${contentType}; boundary=${boundary}`
    }

    win.loadURL(url, loadOptions) // existing webContents will be navigated automatically
  }
  event.newGuest = win
})

Event: 'will-navigate'

Returns:

  • event Event
  • 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 webContents.loadURL and webContents.back.

It is also 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.

Calling event.preventDefault() will prevent the navigation.

Event: 'did-start-navigation'

Returns:

  • event Event
  • url String
  • isInPlace Boolean
  • isMainFrame Boolean
  • frameProcessId Integer
  • frameRoutingId Integer

Emitted when any frame (including main) starts navigating. isInplace will be true for in-page navigations.

Event: 'will-redirect'

Returns:

  • event Event
  • url String
  • isInPlace Boolean
  • isMainFrame Boolean
  • frameProcessId Integer
  • frameRoutingId Integer

Emitted as a server side redirect occurs during navigation. For example a 302 redirect.

This event will be emitted after did-start-navigation and always before the did-redirect-navigation event for the same navigation.

Calling event.preventDefault() will prevent the navigation (not just the redirect).

Event: 'did-redirect-navigation'

Returns:

  • event Event
  • url String
  • isInPlace Boolean
  • isMainFrame Boolean
  • frameProcessId Integer
  • frameRoutingId Integer

Emitted after a server side redirect occurs during navigation. For example a 302 redirect.

This event cannot be prevented, if you want to prevent redirects you should checkout out the will-redirect event above.

Event: 'did-navigate'

Returns:

  • event Event
  • url String
  • httpResponseCode Integer - -1 for non HTTP navigations
  • httpStatusText String - empty for non HTTP navigations

Emitted when a main frame 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-frame-navigate'

Returns:

  • event Event
  • url String
  • httpResponseCode Integer - -1 for non HTTP navigations
  • httpStatusText String - empty for non HTTP navigations,
  • isMainFrame Boolean
  • frameProcessId Integer
  • frameRoutingId Integer

Emitted when any frame 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:

  • event Event
  • url String
  • isMainFrame Boolean
  • frameProcessId Integer
  • frameRoutingId Integer

Emitted when an in-page navigation happened in any frame.

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: 'will-prevent-unload'

Returns:

  • event Event

Emitted when a beforeunload event handler is attempting to cancel a page unload.

Calling event.preventDefault() will ignore the beforeunload event handler and allow the page to be unloaded.

const { BrowserWindow, dialog } = require('electron')
const win = new BrowserWindow({ width: 800, height: 600 })
win.webContents.on('will-prevent-unload', (event) => {
  const choice = dialog.showMessageBoxSync(win, {
    type: 'question',
    buttons: ['Leave', 'Stay'],
    title: 'Do you want to leave this site?',
    message: 'Changes you made may not be saved.',
    defaultId: 0,
    cancelId: 1
  })
  const leave = (choice === 0)
  if (leave) {
    event.preventDefault()
  }
})

Event: 'crashed' Deprecated

Returns:

  • event Event
  • killed Boolean

Emitted when the renderer process crashes or is killed.

Deprecated: This event is superceded by the render-process-gone event which contains more information about why the render process disappeared. It isn't always because it crashed. The killed boolean can be replaced by checking reason === 'killed' when you switch to that event.

Event: 'render-process-gone'

Returns:

  • event Event
  • details Object
    • reason String - The reason the render process is gone. Possible values:
      • clean-exit - Process exited with an exit code of zero
      • abnormal-exit - Process exited with a non-zero exit code
      • killed - Process was sent a SIGTERM or otherwise killed externally
      • crashed - Process crashed
      • oom - Process ran out of memory
      • launch-failed - Process never successfully launched
      • integrity-failure - Windows code integrity checks failed

Emitted when the renderer process unexpectedly disappears. This is normally because it was crashed or killed.

Event: 'unresponsive'

Emitted when the web page becomes unresponsive.

Event: 'responsive'

Emitted when the unresponsive web page becomes responsive again.

Event: 'plugin-crashed'

Returns:

  • event Event
  • name String
  • version String

Emitted when a plugin process has crashed.

Event: 'destroyed'

Emitted when webContents is destroyed.

Event: 'before-input-event'

Returns:

Emitted before dispatching the keydown and keyup events in the page. Calling event.preventDefault will prevent the page keydown/keyup events and the menu shortcuts.

To only prevent the menu shortcuts, use setIgnoreMenuShortcuts:

const { BrowserWindow } = require('electron')

const win = new BrowserWindow({ width: 800, height: 600 })

win.webContents.on('before-input-event', (event, input) => {
  // For example, only enable application menu keyboard shortcuts when
  // Ctrl/Cmd are down.
  win.webContents.setIgnoreMenuShortcuts(!input.control && !input.meta)
})

Event: 'enter-html-full-screen'

Emitted when the window enters a full-screen state triggered by HTML API.

Event: 'leave-html-full-screen'

Emitted when the window leaves a full-screen state triggered by HTML API.

Event: 'zoom-changed'

Returns:

  • event Event
  • zoomDirection String - Can be in or out.

Emitted when the user is requesting to change the zoom level using the mouse wheel.

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.

Event: 'certificate-error'

Returns:

  • event Event
  • url String
  • error String - The error code.
  • certificate Certificate
  • callback Function
    • isTrusted Boolean - Indicates whether the certificate can be considered trusted.

Emitted when failed to verify the certificate for url.

The usage is the same with the certificate-error event of app.

Event: 'select-client-certificate'

Returns:

  • event Event
  • url URL
  • certificateList Certificate[]
  • callback Function
    • certificate Certificate - Must be a certificate from the given list.

Emitted when a client certificate is requested.

The usage is the same with the select-client-certificate event of app.

Event: 'login'

Returns:

  • event Event
  • authenticationResponseDetails Object
    • url URL
  • authInfo Object
    • isProxy Boolean
    • scheme String
    • host String
    • port Integer
    • realm String
  • callback Function
    • username String (optional)
    • password String (optional)

Emitted when webContents wants to do basic auth.

The usage is the same with the login event of app.

Event: 'found-in-page'

Returns:

  • event Event
  • 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

Emitted when a result is available for [webContents.findInPage] request.

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:

  • event Event
  • color (String | null) - Theme color is in format of '#rrggbb'. It is null when no theme color is set.

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:

  • event Event
  • url String

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

Event: 'cursor-changed'

Returns:

  • event Event
  • type String
  • image NativeImage (optional)
  • scale Float (optional) - scaling factor for the custom cursor.
  • size Size (optional) - the size of the image.
  • hotspot Point (optional) - coordinates of the custom cursor's hotspot.

Emitted when the cursor's type changes. The type parameter can be default, crosshair, pointer, text, wait, help, e-resize, n-resize, ne-resize, nw-resize, s-resize, se-resize, sw-resize, w-resize, ns-resize, ew-resize, nesw-resize, nwse-resize, col-resize, row-resize, m-panning, e-panning, n-panning, ne-panning, nw-panning, s-panning, se-panning, sw-panning, w-panning, move, vertical-text, cell, context-menu, alias, progress, nodrop, copy, none, not-allowed, zoom-in, zoom-out, grab, grabbing or custom.

If the type parameter is custom, the image parameter will hold the custom cursor image in a NativeImage, and scale, size and hotspot will hold additional information about the custom cursor.

Event: 'context-menu'

Returns:

  • event Event
  • params Object
    • x Integer - x coordinate.
    • y Integer - y coordinate.
    • linkURL String - URL of the link that encloses the node the context menu was invoked on.
    • linkText String - Text associated with the link. May be an empty string if the contents of the link are an image.
    • pageURL String - URL of the top level page that the context menu was invoked on.
    • frameURL String - URL of the subframe that the context menu was invoked on.
    • srcURL String - Source URL for the element that the context menu was invoked on. Elements with source URLs are images, audio and video.
    • mediaType String - Type of the node the context menu was invoked on. Can be none, image, audio, video, canvas, file or plugin.
    • hasImageContents Boolean - Whether the context menu was invoked on an image which has non-empty contents.
    • isEditable Boolean - Whether the context is editable.
    • selectionText String - Text of the selection that the context menu was invoked on.
    • titleText String - Title or alt text of the selection that the context was invoked on.
    • misspelledWord String - The misspelled word under the cursor, if any.
    • dictionarySuggestions String[] - An array of suggested words to show the user to replace the misspelledWord. Only available if there is a misspelled word and spellchecker is enabled.
    • frameCharset String - The character encoding of the frame on which the menu was invoked.
    • inputFieldType String - If the context menu was invoked on an input field, the type of that field. Possible values are none, plainText, password, other.
    • menuSourceType String - Input source that invoked the context menu. Can be none, mouse, keyboard, touch or touchMenu.
    • mediaFlags Object - The flags for the media element the context menu was invoked on.
      • inError Boolean - Whether the media element has crashed.
      • isPaused Boolean - Whether the media element is paused.
      • isMuted Boolean - Whether the media element is muted.
      • hasAudio Boolean - Whether the media element has audio.
      • isLooping Boolean - Whether the media element is looping.
      • isControlsVisible Boolean - Whether the media element's controls are visible.
      • canToggleControls Boolean - Whether the media element's controls are toggleable.
      • canRotate Boolean - Whether the media element can be rotated.
    • editFlags Object - These flags indicate whether the renderer believes it is able to perform the corresponding action.
      • canUndo Boolean - Whether the renderer believes it can undo.
      • canRedo Boolean - Whether the renderer believes it can redo.
      • canCut Boolean - Whether the renderer believes it can cut.
      • canCopy Boolean - Whether the renderer believes it can copy
      • canPaste Boolean - Whether the renderer believes it can paste.
      • canDelete Boolean - Whether the renderer believes it can delete.
      • canSelectAll Boolean - Whether the renderer believes it can select all.

Emitted when there is a new context menu that needs to be handled.

Event: 'select-bluetooth-device'

Returns:

Emitted when bluetooth device needs to be selected on call to navigator.bluetooth.requestDevice. To use navigator.bluetooth api webBluetooth should be enabled. If event.preventDefault is not called, first available device will be selected. callback should be called with deviceId to be selected, passing empty string to callback will cancel the request.

const { app, BrowserWindow } = require('electron')

let win = null
app.commandLine.appendSwitch('enable-experimental-web-platform-features')

app.whenReady().then(() => {
  win = new BrowserWindow({ width: 800, height: 600 })
  win.webContents.on('select-bluetooth-device', (event, deviceList, callback) => {
    event.preventDefault()
    const result = deviceList.find((device) => {
      return device.deviceName === 'test'
    })
    if (!result) {
      callback('')
    } else {
      callback(result.deviceId)
    }
  })
})

Event: 'paint'

Returns:

Emitted when a new frame is generated. Only the dirty area is passed in the buffer.

const { BrowserWindow } = require('electron')

const win = new BrowserWindow({ webPreferences: { offscreen: true } })
win.webContents.on('paint', (event, dirty, image) => {
  // updateBitmap(dirty, image.getBitmap())
})
win.loadURL('http://github.com')

Event: 'devtools-reload-page'

Emitted when the devtools window instructs the webContents to reload

Event: 'will-attach-webview'

Returns:

  • event Event
  • webPreferences WebPreferences - The web preferences that will be used by the guest page. This object can be modified to adjust the preferences for the guest page.
  • params Record<string, string> - The other <webview> parameters such as the src URL. This object can be modified to adjust the parameters of the guest page.

Emitted when a <webview>'s web contents is being attached to this web contents. Calling event.preventDefault() will destroy the guest page.

This event can be used to configure webPreferences for the webContents of a <webview> before it's loaded, and provides the ability to set settings that can't be set via <webview> attributes.

Note: The specified preload script option will appear as preloadURL (not preload) in the webPreferences object emitted with this event.

Event: 'did-attach-webview'

Returns:

  • event Event
  • webContents WebContents - The guest web contents that is used by the <webview>.

Emitted when a <webview> has been attached to this web contents.

Event: 'console-message'

Returns:

  • event Event
  • 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

Emitted when the associated window logs a console message.

Event: 'preload-error'

Returns:

  • event Event
  • preloadPath String
  • error Error

Emitted when the preload script preloadPath throws an unhandled exception error.

Event: 'ipc-message'

Returns:

  • event Event
  • channel String
  • ...args any[]

Emitted when the renderer process sends an asynchronous message via ipcRenderer.send().

Event: 'ipc-message-sync'

Returns:

  • event Event
  • channel String
  • ...args any[]

Emitted when the renderer process sends a synchronous message via ipcRenderer.sendSync().

Event: 'desktop-capturer-get-sources'

Returns:

  • event Event

Emitted when desktopCapturer.getSources() is called in the renderer process. Calling event.preventDefault() will make it return empty sources.

Event: 'remote-require'

Returns:

  • event IpcMainEvent
  • moduleName String

Emitted when remote.require() is called in the renderer process. Calling event.preventDefault() will prevent the module from being returned. Custom value can be returned by setting event.returnValue.

Event: 'remote-get-global'

Returns:

  • event IpcMainEvent
  • globalName String

Emitted when remote.getGlobal() is called in the renderer process. Calling event.preventDefault() will prevent the global from being returned. Custom value can be returned by setting event.returnValue.

Event: 'remote-get-builtin'

Returns:

  • event IpcMainEvent
  • moduleName String

Emitted when remote.getBuiltin() is called in the renderer process. Calling event.preventDefault() will prevent the module from being returned. Custom value can be returned by setting event.returnValue.

Event: 'remote-get-current-window'

Returns:

  • event IpcMainEvent

Emitted when remote.getCurrentWindow() is called in the renderer process. Calling event.preventDefault() will prevent the object from being returned. Custom value can be returned by setting event.returnValue.

Event: 'remote-get-current-web-contents'

Returns:

  • event IpcMainEvent

Emitted when remote.getCurrentWebContents() is called in the renderer process. Calling event.preventDefault() will prevent the object from being returned. Custom value can be returned by setting event.returnValue.

Instance Methods

contents.loadURL(url[, options])

  • url String
  • 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[] | UploadBlob[]) (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). A noop rejection handler is already attached, which avoids unhandled rejection errors.

Loads the url in the window. The url must contain the protocol prefix, e.g. the http:// or file://. If the load should bypass http cache then use the pragma header to achieve it.

const { webContents } = require('electron')
const options = { extraHeaders: 'pragma: no-cache\n' }
webContents.loadURL('https://github.com', options)

contents.loadFile(filePath[, options])

  • filePath String
  • options Object (optional)
    • query Record<String, String> (optional) - Passed to url.format().
    • search String (optional) - Passed to url.format().
    • hash String (optional) - Passed to url.format().

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 given file in the window, filePath should be a path to an HTML file relative to the root of your application. For instance an app structure like this:

| root
| - package.json
| - src
|   - main.js
|   - index.html

Would require code like this

win.loadFile('src/index.html')

contents.downloadURL(url)

  • url String

Initiates a download of the resource at url without navigating. The will-download event of session will be triggered.

contents.getURL()

Returns String - The URL of the current web page.

const { BrowserWindow } = require('electron')
const win = new BrowserWindow({ width: 800, height: 600 })
win.loadURL('http://github.com').then(() => {
  const currentURL = win.webContents.getURL()
  console.log(currentURL)
})

contents.getTitle()

Returns String - The title of the current web page.

contents.isDestroyed()

Returns Boolean - Whether the web page is destroyed.

contents.focus()

Focuses the web page.

contents.isFocused()

Returns Boolean - Whether the web page is focused.

contents.isLoading()

Returns Boolean - Whether web page is still loading resources.

contents.isLoadingMainFrame()

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

contents.isWaitingForResponse()

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

contents.stop()

Stops any pending navigation.

contents.reload()

Reloads the current web page.

contents.reloadIgnoringCache()

Reloads current page and ignores cache.

contents.canGoBack()

Returns Boolean - Whether the browser can go back to previous web page.

contents.canGoForward()

Returns Boolean - Whether the browser can go forward to next web page.

contents.canGoToOffset(offset)

  • offset Integer

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

contents.clearHistory()

Clears the navigation history.

contents.goBack()

Makes the browser go back a web page.

contents.goForward()

Makes the browser go forward a web page.

contents.goToIndex(index)

  • index Integer

Navigates browser to the specified absolute web page index.

contents.goToOffset(offset)

  • offset Integer

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

contents.isCrashed()

Returns Boolean - Whether the renderer process has crashed.

contents.forcefullyCrashRenderer()

Forcefully terminates the renderer process that is currently hosting this webContents. This will cause the render-process-gone event to be emitted with the reason=killed || reason=crashed. Please note that some webContents share renderer processes and therefore calling this method may also crash the host process for other webContents as well.

Calling reload() immediately after calling this method will force the reload to occur in a new process. This should be used when this process is unstable or unusable, for instance in order to recover from the unresponsive event.

contents.on('unresponsive', async () => {
  const { response } = await dialog.showMessageBox({
    message: 'App X has become unresponsive',
    title: 'Do you want to try forcefully reloading the app?',
    buttons: ['OK', 'Cancel'],
    cancelId: 1
  })
  if (response === 0) {
    contents.forcefullyCrashRenderer()
    contents.reload()
  }
})

contents.setUserAgent(userAgent)

  • userAgent String

Overrides the user agent for this web page.

contents.getUserAgent()

Returns String - The user agent for this web page.

contents.insertCSS(css[, options])

  • css String
  • options Object (optional)
    • cssOrigin String (optional) - Can be either 'user' or 'author'; Specifying 'user' enables you to prevent websites from overriding the CSS you insert. Default is 'author'.

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

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

contents.on('did-finish-load', () => {
  contents.insertCSS('html, body { background-color: #f00; }')
})

contents.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 contents.insertCSS(css).

contents.on('did-finish-load', async () => {
  const key = await contents.insertCSS('html, body { background-color: #f00; }')
  contents.removeInsertedCSS(key)
})

contents.executeJavaScript(code[, userGesture])

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

In the browser window some HTML APIs like requestFullScreen can only be invoked by a gesture from the user. Setting userGesture to true will remove this limitation.

Code execution will be suspended until web page stop loading.

contents.executeJavaScript('fetch("https://jsonplaceholder.typicode.com/users/1").then(resp => resp.json())', true)
  .then((result) => {
    console.log(result) // Will be the JSON object from the fetch call
  })

contents.executeJavaScriptInIsolatedWorld(worldId, scripts[, userGesture])

  • worldId Integer - The ID of the world to run the javascript in, 0 is the default world, 999 is the world used by Electron's contextIsolation feature. You can provide any integer here.
  • scripts WebSource[]
  • userGesture Boolean (optional) - Default is 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.

Works like executeJavaScript but evaluates scripts in an isolated context.

contents.setIgnoreMenuShortcuts(ignore)

  • ignore Boolean

Ignore application menu shortcuts while this web contents is focused.

contents.setAudioMuted(muted)

  • muted Boolean

Mute the audio on the current web page.

contents.isAudioMuted()

Returns Boolean - Whether this page has been muted.

contents.isCurrentlyAudible()

Returns Boolean - Whether audio is currently playing.

contents.setZoomFactor(factor)

  • factor Double - Zoom factor; default is 1.0.

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

The factor must be greater than 0.0.

contents.getZoomFactor()

Returns Number - the current zoom factor.

contents.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.

contents.getZoomLevel()

Returns Number - the current zoom level.

contents.setVisualZoomLevelLimits(minimumLevel, maximumLevel)

  • minimumLevel Number
  • maximumLevel Number

Returns Promise<void>

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

NOTE: Visual zoom is disabled by default in Electron. To re-enable it, call:

contents.setVisualZoomLevelLimits(1, 3)

contents.undo()

Executes the editing command undo in web page.

contents.redo()

Executes the editing command redo in web page.

contents.cut()

Executes the editing command cut in web page.

contents.copy()

Executes the editing command copy in web page.

contents.copyImageAt(x, y)

  • x Integer
  • y Integer

Copy the image at the given position to the clipboard.

contents.paste()

Executes the editing command paste in web page.

contents.pasteAndMatchStyle()

Executes the editing command pasteAndMatchStyle in web page.

contents.delete()

Executes the editing command delete in web page.

contents.selectAll()

Executes the editing command selectAll in web page.

contents.unselect()

Executes the editing command unselect in web page.

contents.replace(text)

  • text String

Executes the editing command replace in web page.

contents.replaceMisspelling(text)

  • text String

Executes the editing command replaceMisspelling in web page.

contents.insertText(text)

  • text String

Returns Promise<void>

Inserts text to the focused element.

contents.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.
    • wordStart Boolean (optional) - Whether to look only at the start of words. defaults to false.
    • medialCapitalAsWordStart Boolean (optional) - When combined with wordStart, accepts a match in the middle of a word if the match begins with an uppercase letter followed by a lowercase or non-letter. Accepts several other intra-word matches, 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.

contents.stopFindInPage(action)

  • action String - Specifies the action to take place when ending [webContents.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 webContents with the provided action.

const { webContents } = require('electron')
webContents.on('found-in-page', (event, result) => {
  if (result.finalUpdate) webContents.stopFindInPage('clearSelection')
})

const requestId = webContents.findInPage('api')
console.log(requestId)

contents.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.

contents.isBeingCaptured()

Returns Boolean - Whether this page is being captured. It returns true when the capturer count is large then 0.

contents.incrementCapturerCount([size, stayHidden])

  • size Size (optional) - The preferred size for the capturer.
  • stayHidden Boolean (optional) - Keep the page hidden instead of visible.

Increase the capturer count by one. The page is considered visible when its browser window is hidden and the capturer count is non-zero. If you would like the page to stay hidden, you should ensure that stayHidden is set to true.

This also affects the Page Visibility API.

contents.decrementCapturerCount([stayHidden])

  • stayHidden Boolean (optional) - Keep the page in hidden state instead of visible.

Decrease the capturer count by one. The page will be set to hidden or occluded state when its browser window is hidden or occluded and the capturer count reaches zero. If you want to decrease the hidden capturer count instead you should set stayHidden to true.

contents.getPrinters()

Get the system printer list.

Returns PrinterInfo[]

contents.print([options], [callback])

  • 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. On macOS, only one 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).
    • 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.
  • callback Function (optional)
    • success Boolean - Indicates success of the print call.
    • failureReason String - Error description called back if the print fails.

When a custom pageSize is passed, Chromium attempts to validate platform specific minimum values for width_microns and height_microns. Width and height must both be minimum 353 microns but may be higher on some operating systems.

Prints window's web page. When silent is set to true, Electron will pick the system's default printer if deviceName is empty and the default settings for printing.

Use page-break-before: always; CSS style to force to print to a new page.

Example usage:

const options = {
  silent: true,
  deviceName: 'My-Printer',
  pageRanges: [{
    from: 0,
    to: 1
  }]
}
win.webContents.print(options, (success, errorType) => {
  if (!success) console.log(errorType)
})

contents.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.
    • 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.
      • 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 and width in microns.
    • printBackground Boolean (optional) - Whether to print CSS backgrounds.
    • printSelectionOnly Boolean (optional) - Whether to print selection only.

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

Prints window's web page as PDF with Chromium's preview printing custom settings.

The landscape will be ignored if @page CSS at-rule is used in the web page.

By default, an empty options will be regarded as:

{
  marginsType: 0,
  printBackground: false,
  printSelectionOnly: false,
  landscape: false,
  pageSize: 'A4',
  scaleFactor: 100
}

Use page-break-before: always; CSS style to force to print to a new page.

An example of webContents.printToPDF:

const { BrowserWindow } = require('electron')
const fs = require('fs')
const path = require('path')
const os = require('os')

const win = new BrowserWindow({ width: 800, height: 600 })
win.loadURL('http://github.com')

win.webContents.on('did-finish-load', () => {
  // Use default printing options
  win.webContents.printToPDF({}).then(data => {
    const pdfPath = path.join(os.homedir(), 'Desktop', 'temp.pdf')
    fs.writeFile(pdfPath, data, (error) => {
      if (error) throw error
      console.log(`Wrote PDF successfully to ${pdfPath}`)
    })
  }).catch(error => {
    console.log(`Failed to write PDF to ${pdfPath}: `, error)
  })
})

contents.addWorkSpace(path)

  • path String

Adds the specified path to DevTools workspace. Must be used after DevTools creation:

const { BrowserWindow } = require('electron')
const win = new BrowserWindow()
win.webContents.on('devtools-opened', () => {
  win.webContents.addWorkSpace(__dirname)
})

contents.removeWorkSpace(path)

  • path String

Removes the specified path from DevTools workspace.

contents.setDevToolsWebContents(devToolsWebContents)

  • devToolsWebContents WebContents

Uses the devToolsWebContents as the target WebContents to show devtools.

The devToolsWebContents must not have done any navigation, and it should not be used for other purposes after the call.

By default Electron manages the devtools by creating an internal WebContents with native view, which developers have very limited control of. With the setDevToolsWebContents method, developers can use any WebContents to show the devtools in it, including BrowserWindow, BrowserView and <webview> tag.

Note that closing the devtools does not destroy the devToolsWebContents, it is caller's responsibility to destroy devToolsWebContents.

An example of showing devtools in a <webview> tag:

<html>
<head>
  <style type="text/css">
    * { margin: 0; }
    #browser { height: 70%; }
    #devtools { height: 30%; }
  </style>
</head>
<body>
  <webview id="browser" src="https://github.com"></webview>
  <webview id="devtools" src="about:blank"></webview>
  <script>
    const { webContents } = require('electron').remote
    const emittedOnce = (element, eventName) => new Promise(resolve => {
      element.addEventListener(eventName, event => resolve(event), { once: true })
    })
    const browserView = document.getElementById('browser')
    const devtoolsView = document.getElementById('devtools')
    const browserReady = emittedOnce(browserView, 'dom-ready')
    const devtoolsReady = emittedOnce(devtoolsView, 'dom-ready')
    Promise.all([browserReady, devtoolsReady]).then(() => {
      const browser = webContents.fromId(browserView.getWebContentsId())
      const devtools = webContents.fromId(devtoolsView.getWebContentsId())
      browser.setDevToolsWebContents(devtools)
      browser.openDevTools()
    })
  </script>
</body>
</html>

An example of showing devtools in a BrowserWindow:

const { app, BrowserWindow } = require('electron')

let win = null
let devtools = null

app.whenReady().then(() => {
  win = new BrowserWindow()
  devtools = new BrowserWindow()
  win.loadURL('https://github.com')
  win.webContents.setDevToolsWebContents(devtools.webContents)
  win.webContents.openDevTools({ mode: 'detach' })
})

contents.openDevTools([options])

  • options Object (optional)
    • mode String - Opens the devtools with specified dock state, can be right, bottom, undocked, detach. Defaults to last used dock state. In undocked mode it's possible to dock back. In detach mode it's not.
    • activate Boolean (optional) - Whether to bring the opened devtools window to the foreground. The default is true.

Opens the devtools.

When contents is a <webview> tag, the mode would be detach by default, explicitly passing an empty mode can force using last used dock state.

contents.closeDevTools()

Closes the devtools.

contents.isDevToolsOpened()

Returns Boolean - Whether the devtools is opened.

contents.isDevToolsFocused()

Returns Boolean - Whether the devtools view is focused .

contents.toggleDevTools()

Toggles the developer tools.

contents.inspectElement(x, y)

  • x Integer
  • y Integer

Starts inspecting element at position (x, y).

contents.inspectSharedWorker()

Opens the developer tools for the shared worker context.

contents.inspectSharedWorkerById(workerId)

  • workerId String

Inspects the shared worker based on its ID.

contents.getAllSharedWorkers()

Returns SharedWorkerInfo[] - Information about all Shared Workers.

contents.inspectServiceWorker()

Opens the developer tools for the service worker context.

contents.send(channel, ...args)

  • channel String
  • ...args any[]

Send an asynchronous message to the renderer process via channel, along with arguments. Arguments will be serialized with the Structured Clone Algorithm, just like postMessage, so prototype chains will not be included. Sending Functions, Promises, Symbols, WeakMaps, or WeakSets will throw an exception.

NOTE: Sending non-standard JavaScript types such as DOM objects or special Electron objects is deprecated, and will begin throwing an exception starting with Electron 9.

The renderer process can handle the message by listening to channel with the ipcRenderer module.

An example of sending messages from the main process to the renderer process:

// In the main process.
const { app, BrowserWindow } = require('electron')
let win = null

app.whenReady().then(() => {
  win = new BrowserWindow({ width: 800, height: 600 })
  win.loadURL(`file://${__dirname}/index.html`)
  win.webContents.on('did-finish-load', () => {
    win.webContents.send('ping', 'whoooooooh!')
  })
})

<!-- index.html -->
<html>
<body>
  <script>
    require('electron').ipcRenderer.on('ping', (event, message) => {
      console.log(message) // Prints 'whoooooooh!'
    })
  </script>
</body>
</html>

contents.sendToFrame(frameId, channel, ...args)

  • frameId Integer
  • channel String
  • ...args any[]

Send an asynchronous message to a specific frame in a renderer process via channel, along with arguments. Arguments will be serialized with the Structured Clone Algorithm, just like postMessage, so prototype chains will not be included. Sending Functions, Promises, Symbols, WeakMaps, or WeakSets will throw an exception.

NOTE: Sending non-standard JavaScript types such as DOM objects or special Electron objects is deprecated, and will begin throwing an exception starting with Electron 9.

The renderer process can handle the message by listening to channel with the ipcRenderer module.

If you want to get the frameId of a given renderer context you should use the webFrame.routingId value. E.g.

// In a renderer process
console.log('My frameId is:', require('electron').webFrame.routingId)

You can also read frameId from all incoming IPC messages in the main process.

// In the main process
ipcMain.on('ping', (event) => {
  console.info('Message came from frameId:', event.frameId)
})

contents.postMessage(channel, message, [transfer])

  • channel String
  • message any
  • transfer MessagePortMain[] (optional)

Send a message to the renderer process, optionally transferring ownership of zero or more [MessagePortMain][] objects.

The transferred MessagePortMain objects will be available in the renderer process by accessing the ports property of the emitted event. When they arrive in the renderer, they will be native DOM MessagePort objects.

For example:

// Main process
const { port1, port2 } = new MessageChannelMain()
webContents.postMessage('port', { message: 'hello' }, [port1])

// Renderer process
ipcRenderer.on('port', (e, msg) => {
  const [port] = e.ports
  // ...
})

contents.enableDeviceEmulation(parameters)

  • parameters Object
    • screenPosition String - Specify the screen type to emulate (default: desktop):
      • desktop - Desktop screen type.
      • mobile - Mobile screen type.
    • screenSize Size - Set the emulated screen size (screenPosition == mobile).
    • viewPosition Point - Position the view on the screen (screenPosition == mobile) (default: { x: 0, y: 0 }).
    • deviceScaleFactor Integer - Set the device scale factor (if zero defaults to original device scale factor) (default: 0).
    • viewSize Size - Set the emulated view size (empty means no override)
    • scale Float - Scale of emulated view inside available space (not in fit to view mode) (default: 1).

Enable device emulation with the given parameters.

contents.disableDeviceEmulation()

Disable device emulation enabled by webContents.enableDeviceEmulation.

contents.sendInputEvent(inputEvent)

Sends an input event to the page. Note: The BrowserWindow containing the contents needs to be focused for sendInputEvent() to work.

contents.beginFrameSubscription([onlyDirty ,]callback)

  • onlyDirty Boolean (optional) - Defaults to false.
  • callback Function

Begin subscribing for presentation events and captured frames, the callback will be called with callback(image, dirtyRect) when there is a presentation event.

The image is an instance of NativeImage that stores the captured frame.

The dirtyRect is an object with x, y, width, height properties that describes which part of the page was repainted. If onlyDirty is set to true, image will only contain the repainted area. onlyDirty defaults to false.

contents.endFrameSubscription()

End subscribing for frame presentation events.

contents.startDrag(item)

  • item Object
    • file String[] | String - The path(s) to the file(s) being dragged.
    • icon NativeImage | String - The image must be non-empty on macOS.

Sets the item as dragging item for current drag-drop operation, file is the absolute path of the file to be dragged, and icon is the image showing under the cursor when dragging.

contents.savePage(fullPath, saveType)

  • fullPath String - The full file path.
  • saveType String - Specify the save type.
    • HTMLOnly - Save only the HTML of the page.
    • HTMLComplete - Save complete-html page.
    • MHTML - Save complete-html page as MHTML.

Returns Promise<void> - resolves if the page is saved.

const { BrowserWindow } = require('electron')
const win = new BrowserWindow()

win.loadURL('https://github.com')

win.webContents.on('did-finish-load', async () => {
  win.webContents.savePage('/tmp/test.html', 'HTMLComplete').then(() => {
    console.log('Page was saved successfully.')
  }).catch(err => {
    console.log(err)
  })
})

contents.showDefinitionForSelection() macOS

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

contents.isOffscreen()

Returns Boolean - Indicates whether offscreen rendering is enabled.

contents.startPainting()

If offscreen rendering is enabled and not painting, start painting.

contents.stopPainting()

If offscreen rendering is enabled and painting, stop painting.

contents.isPainting()

Returns Boolean - If offscreen rendering is enabled returns whether it is currently painting.

contents.setFrameRate(fps)

  • fps Integer

If offscreen rendering is enabled sets the frame rate to the specified number. Only values between 1 and 60 are accepted.

contents.getFrameRate()

Returns Integer - If offscreen rendering is enabled returns the current frame rate.

contents.invalidate()

Schedules a full repaint of the window this web contents is in.

If offscreen rendering is enabled invalidates the frame and generates a new one through the 'paint' event.

contents.getWebRTCIPHandlingPolicy()

Returns String - Returns the WebRTC IP Handling Policy.

contents.setWebRTCIPHandlingPolicy(policy)

  • policy String - Specify the WebRTC IP Handling Policy.
    • default - Exposes user's public and local IPs. This is the default behavior. When this policy is used, WebRTC has the right to enumerate all interfaces and bind them to discover public interfaces.
    • default_public_interface_only - Exposes user's public IP, but does not expose user's local IP. When this policy is used, WebRTC should only use the default route used by http. This doesn't expose any local addresses.
    • default_public_and_private_interfaces - Exposes user's public and local IPs. When this policy is used, WebRTC should only use the default route used by http. This also exposes the associated default private address. Default route is the route chosen by the OS on a multi-homed endpoint.
    • disable_non_proxied_udp - Does not expose public or local IPs. When this policy is used, WebRTC should only use TCP to contact peers or servers unless the proxy server supports UDP.

Setting the WebRTC IP handling policy allows you to control which IPs are exposed via WebRTC. See BrowserLeaks for more details.

contents.getOSProcessId()

Returns Integer - The operating system pid of the associated renderer process.

contents.getProcessId()

Returns Integer - The Chromium internal pid of the associated renderer. Can be compared to the frameProcessId passed by frame specific navigation events (e.g. did-frame-navigate)

contents.takeHeapSnapshot(filePath)

  • filePath String - Path to the output file.

Returns Promise<void> - Indicates whether the snapshot has been created successfully.

Takes a V8 heap snapshot and saves it to filePath.

contents.getBackgroundThrottling()

Returns Boolean - whether or not this WebContents will throttle animations and timers when the page becomes backgrounded. This also affects the Page Visibility API.

contents.setBackgroundThrottling(allowed)

  • allowed Boolean

Controls whether or not this WebContents will throttle animations and timers when the page becomes backgrounded. This also affects the Page Visibility API.

contents.getType()

Returns String - the type of the webContent. Can be backgroundPage, window, browserView, remote, webview or offscreen.

Instance Properties

contents.audioMuted

A Boolean property that determines whether this page is muted.

contents.userAgent

A String property that determines the user agent for this web page.

contents.zoomLevel

A Number property that determines the zoom level for this web contents.

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.

contents.zoomFactor

A Number property that determines the zoom factor for this web contents.

The zoom factor is the zoom percent divided by 100, so 300% = 3.0.

contents.frameRate

An Integer property that sets the frame rate of the web contents to the specified number. Only values between 1 and 60 are accepted.

Only applicable if offscreen rendering is enabled.

contents.id Readonly

A Integer representing the unique ID of this WebContents. Each ID is unique among all WebContents instances of the entire Electron application.

contents.session Readonly

A Session used by this webContents.

contents.hostWebContents Readonly

A WebContents instance that might own this WebContents.

contents.devToolsWebContents Readonly

A WebContents | null property that represents the of DevTools WebContents associated with a given WebContents.

Note: Users should never store this object because it may become null when the DevTools has been closed.

contents.debugger Readonly

A Debugger instance for this webContents.

contents.backgroundThrottling

A Boolean property that determines whether or not this WebContents will throttle animations and timers when the page becomes backgrounded. This also affects the Page Visibility API.

© GitHub Inc.
Licensed under the MIT license.
https://www.electronjs.org/docs/api/web-contents