electron/docs/api/web-contents.md

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')

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

let 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 or was cancelled, e.g. window.stop() is invoked. The full list of error codes and their meaning is available here.

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-favicon-updated'

Returns:

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

Emitted when page receives favicon urls.

Event: 'new-window'

Returns:

• event Event
• url String
• frameName String
• disposition String - Can be default, foreground-tab, background-tab, new-window, save-to-disk and other.
• options Object - 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.

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) => {
  event.preventDefault()
  const win = new BrowserWindow({ show: false })
  win.once('ready-to-show', () => win.show())
  win.loadURL(url)
  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 can not 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.showMessageBox(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'

Returns:

• event Event
• killed Boolean

Emitted when the renderer process crashes or is 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:

• event Event
• input Object - Input properties.
  • type String - Either keyUp or keyDown.
  • key String - Equivalent to KeyboardEvent.key.
  • code String - Equivalent to KeyboardEvent.code.
  • isAutoRepeat Boolean - Equivalent to KeyboardEvent.repeat.
  • shift Boolean - Equivalent to KeyboardEvent.shiftKey.
  • control Boolean - Equivalent to KeyboardEvent.controlKey.
  • alt Boolean - Equivalent to KeyboardEvent.altKey.
  • meta Boolean - Equivalent to KeyboardEvent.metaKey.

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')

let 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: '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
• request Object
  • method String
  • url URL
  • referrer URL
• authInfo Object
  • isProxy Boolean
  • scheme String
  • host String
  • port Integer
  • realm String
• callback Function
  • username String
  • password String

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 Object - 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'

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

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

Returns:

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

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.
  • 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:

• event Event
• devices BluetoothDevice[]
• callback Function
  • deviceId String

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

Event: 'paint'

Returns:

• event Event
• dirtyRect Rectangle
• image NativeImage - The image data of the whole frame.

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

const { BrowserWindow } = require('electron')

let 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 Object - 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 Object - 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 be 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
• message String
• line Integer
• sourceId String

Emitted when the associated window logs a console message. Will not be emitted for windows with offscreen rendering enabled.

Event: 'remote-require'

Returns:

• event Event
• 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 Event
• 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.

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.

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 Object (optional) - Passed to url.format().
  • search String (optional) - Passed to url.format().
  • hash String (optional) - Passed to url.format().

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

let 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.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)

• css String

Injects CSS into the current web page.

contents.executeJavaScript(code[, userGesture, callback])

• code String
• userGesture Boolean (optional) - Default is false.
• callback Function (optional) - Called after script has been executed.
  • result Any

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.

If the result of the executed code is a promise the callback result will be the resolved value of the promise. We recommend that you use the returned Promise to handle code that results in a Promise.

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.setIgnoreMenuShortcuts(ignore) Experimental

• 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 Number - Zoom factor.

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

contents.getZoomFactor(callback)

• callback Function
  • zoomFactor Number

Sends a request to get current zoom factor, the callback will be called with callback(zoomFactor).

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(callback)

• callback Function
  • zoomLevel Number

Sends a request to get current zoom level, the callback will be called with callback(zoomLevel).

contents.setVisualZoomLevelLimits(minimumLevel, maximumLevel)

• minimumLevel Number
• maximumLevel Number

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

contents.setLayoutZoomLevelLimits(minimumLevel, maximumLevel)

• minimumLevel Number
• maximumLevel Number

Sets the maximum and minimum layout-based (i.e. non-visual) zoom level.

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

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, ]callback)

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

Captures a snapshot of the page within rect. Upon completion callback will be called with callback(image). The image is an instance of NativeImage that stores data of the snapshot. Omitting rect will capture the whole visible page.

contents.hasServiceWorker(callback)

• callback Function
  • hasWorker Boolean

Checks if any ServiceWorker is registered and returns a boolean as response to callback.

contents.unregisterServiceWorker(callback)

• callback Function
  • success Boolean

Unregisters any ServiceWorker if present and returns a boolean as response to callback when the JS promise is fulfilled or false when the JS promise is rejected.

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) - Also prints the background color and image of the web page. Default is false.
  • deviceName String (optional) - Set the printer device name to use. Default is ''.
• callback Function (optional)
  • success Boolean - Indicates success of the print call.

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.

Calling window.print() in web page is equivalent to calling webContents.print({ silent: false, printBackground: false, deviceName: '' }).

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

contents.printToPDF(options, callback)

• options Object
  • marginsType Integer (optional) - Specifies the type of margins to use. Uses 0 for default margin, 1 for no margin, and 2 for minimum margin.
  • pageSize String (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.
  • landscape Boolean (optional) - true for landscape, false for portrait.
• callback Function
  • error Error
  • data Buffer

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

The callback will be called with callback(error, data) on completion. The data is a Buffer that contains the generated PDF data.

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
}

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')

let 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({}, (error, data) => {
    if (error) throw error
    fs.writeFile('/tmp/print.pdf', data, (error) => {
      if (error) throw error
      console.log('Write PDF successfully.')
    })
  })
})

contents.addWorkSpace(path)

• path String

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

const { BrowserWindow } = require('electron')
let 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"></webview>
  <script>
    const browserView = document.getElementById('browser')
    const devtoolsView = document.getElementById('devtools')
    browserView.addEventListener('dom-ready', () => {
      const browser = browserView.getWebContents()
      browser.setDevToolsWebContents(devtoolsView.getWebContents())
      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.once('ready', () => {
  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.

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.inspectServiceWorker()

Opens the developer tools for the service worker context.

contents.send(channel[, arg1][, arg2][, ...])

• channel String
• ...args any[]

Send an asynchronous message to renderer process via channel, you can also send arbitrary arguments. Arguments will be serialized in JSON internally and hence no functions or prototype chain will be included.

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.on('ready', () => {
  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.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(event)

• event Object
  • type String (required) - The type of the event, can be mouseDown, mouseUp, mouseEnter, mouseLeave, contextMenu, mouseWheel, mouseMove, keyDown, keyUp or char.
  • modifiers String[] - An array of modifiers of the event, can include shift, control, alt, meta, isKeypad, isAutoRepeat, leftButtonDown, middleButtonDown, rightButtonDown, capsLock, numLock, left, right.

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

For keyboard events, the event object also have following properties:

• keyCode String (required) - The character that will be sent as the keyboard event. Should only use the valid key codes in Accelerator.

For mouse events, the event object also have following properties:

• x Integer (required)
• y Integer (required)
• button String - The button pressed, can be left, middle, right.
• globalX Integer
• globalY Integer
• movementX Integer
• movementY Integer
• clickCount Integer

For the mouseWheel event, the event object also have following properties:

• deltaX Integer
• deltaY Integer
• wheelTicksX Integer
• wheelTicksY Integer
• accelerationRatioX Integer
• accelerationRatioY Integer
• hasPreciseScrollingDeltas Boolean
• canScroll Boolean

contents.beginFrameSubscription([onlyDirty ,]callback)

• onlyDirty Boolean (optional) - Defaults to false.
• callback Function
  • image NativeImage
  • dirtyRect Rectangle

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 or files Array - The path(s) to the file(s) being dragged.
  • icon NativeImage - 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, callback)

• 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.
• callback Function - (error) => {}.
  • error Error

Returns Boolean - true if the process of saving page has been initiated successfully.

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

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

win.webContents.on('did-finish-load', () => {
  win.webContents.savePage('/tmp/test.html', 'HTMLComplete', (error) => {
    if (!error) console.log('Save page successfully')
  })
})

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.

Instance Properties

contents.id

A Integer representing the unique ID of this WebContents.

contents.session

A Session used by this webContents.

contents.hostWebContents

A WebContents instance that might own this WebContents.

contents.devToolsWebContents

A WebContents of DevTools for this WebContents.

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

contents.debugger

A Debugger instance for this webContents.