electron

webFrame

Customize the rendering of the current web page.

Process: Renderer

webFrame export of the Electron module is an instance of the WebFrame class representing the current frame. Sub-frames can be retrieved by certain properties and methods (e.g. webFrame.firstChild).

An example of zooming current page to 200%.

const { webFrame } = require('electron')

webFrame.setZoomFactor(2)

Methods

The WebFrame class has the following instance methods:

webFrame.setZoomFactor(factor)

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.

webFrame.getZoomFactor()

Returns number - The current zoom factor.

webFrame.setZoomLevel(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.

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

webFrame.getZoomLevel()

Returns number - The current zoom level.

webFrame.setVisualZoomLevelLimits(minimumLevel, maximumLevel)

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

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

webFrame.setVisualZoomLevelLimits(1, 3)

NOTE: Visual zoom only applies to pinch-to-zoom behavior. Cmd+/-/0 zoom shortcuts are controlled by the ‘zoomIn’, ‘zoomOut’, and ‘resetZoom’ MenuItem roles in the application Menu. To disable shortcuts, manually define the Menu and omit zoom roles from the definition.

webFrame.setSpellCheckProvider(language, provider)

Sets a provider for spell checking in input fields and text areas.

If you want to use this method you must disable the builtin spellchecker when you construct the window.

const mainWindow = new BrowserWindow({
  webPreferences: {
    spellcheck: false
  }
})

The provider must be an object that has a spellCheck method that accepts an array of individual words for spellchecking. The spellCheck function runs asynchronously and calls the callback function with an array of misspelt words when complete.

An example of using node-spellchecker as provider:

const { webFrame } = require('electron')
const spellChecker = require('spellchecker')
webFrame.setSpellCheckProvider('en-US', {
  spellCheck (words, callback) {
    setTimeout(() => {
      const spellchecker = require('spellchecker')
      const misspelled = words.filter(x => spellchecker.isMisspelled(x))
      callback(misspelled)
    }, 0)
  }
})

webFrame.insertCSS(css[, options])

Returns string - A key for the inserted CSS that can later be used to remove the CSS via webFrame.removeInsertedCSS(key).

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

webFrame.removeInsertedCSS(key)

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

webFrame.insertText(text)

Inserts text to the focused element.

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

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

webFrame.executeJavaScriptInIsolatedWorld(worldId, scripts[, userGesture, callback])

Returns Promise<any> - A promise that resolves with the result of the executed code or is rejected if execution could not start.

Works like executeJavaScript but evaluates scripts in an isolated context.

Note that when the execution of script fails, the returned promise will not reject and the result would be undefined. This is because Chromium does not dispatch errors of isolated worlds to foreign worlds.

webFrame.setIsolatedWorldInfo(worldId, info)

Set the security origin, content security policy and name of the isolated world. Note: If the csp is specified, then the securityOrigin also has to be specified.

webFrame.getResourceUsage()

Returns Object:

Returns an object describing usage information of Blink’s internal memory caches.

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

This will generate:

{
  images: {
    count: 22,
    size: 2549,
    liveSize: 2542
  },
  cssStyleSheets: { /* same with "images" */ },
  xslStyleSheets: { /* same with "images" */ },
  fonts: { /* same with "images" */ },
  other: { /* same with "images" */ }
}

webFrame.clearCache()

Attempts to free memory that is no longer being used (like images from a previous navigation).

Note that blindly calling this method probably makes Electron slower since it will have to refill these emptied caches, you should only call it if an event in your app has occurred that makes you think your page is actually using less memory (i.e. you have navigated from a super heavy page to a mostly empty one, and intend to stay there).

webFrame.getFrameForSelector(selector)

Returns WebFrame - The frame element in webFrame's document selected by selector, null would be returned if selector does not select a frame or if the frame is not in the current renderer process.

webFrame.findFrameByName(name)

Returns WebFrame - A child of webFrame with the supplied name, null would be returned if there’s no such frame or if the frame is not in the current renderer process.

webFrame.findFrameByRoutingId(routingId)

Returns WebFrame - that has the supplied routingId, null if not found.

webFrame.isWordMisspelled(word)

Returns boolean - True if the word is misspelled according to the built in spellchecker, false otherwise. If no dictionary is loaded, always return false.

webFrame.getWordSuggestions(word)

Returns string[] - A list of suggested words for a given word. If the word is spelled correctly, the result will be empty.

Properties

webFrame.top Readonly

A WebFrame | null representing top frame in frame hierarchy to which webFrame belongs, the property would be null if top frame is not in the current renderer process.

webFrame.opener Readonly

A WebFrame | null representing the frame which opened webFrame, the property would be null if there’s no opener or opener is not in the current renderer process.

webFrame.parent Readonly

A WebFrame | null representing parent frame of webFrame, the property would be null if webFrame is top or parent is not in the current renderer process.

webFrame.firstChild Readonly

A WebFrame | null representing the first child frame of webFrame, the property would be null if webFrame has no children or if first child is not in the current renderer process.

webFrame.nextSibling Readonly

A WebFrame | null representing next sibling frame, the property would be null if webFrame is the last frame in its parent or if the next sibling is not in the current renderer process.

webFrame.routingId Readonly

An Integer representing the unique frame id in the current renderer process. Distinct WebFrame instances that refer to the same underlying frame will have the same routingId.

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