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 top frame of the current BrowserWindow. 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)

• 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.

webFrame.getZoomFactor()

Returns Number - The current zoom factor.

webFrame.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.

webFrame.getZoomLevel()

Returns Number - The current zoom level.

webFrame.setVisualZoomLevelLimits(minimumLevel, maximumLevel)

• minimumLevel Number
• maximumLevel Number

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)

webFrame.setSpellCheckProvider(language, provider)

• language String
• provider Object
  • spellCheck Function
    • words String[]
    • callback Function
      • misspeltWords String[]

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)

• css String - CSS source code.

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)

• key String

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)

• text String

Inserts text to the focused element.

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

• code String
• userGesture Boolean (optional) - Default is false.
• callback Function (optional) - Called after script has been executed. Unless the frame is suspended (e.g. showing a modal alert), execution will be synchronous and the callback will be invoked before the method returns. For compatibility with an older version of this method, the error parameter is second.
  • result Any
  • error Error

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])

• worldId Integer - The ID of the world to run the javascript in, 0 is the default main world (where content runs), 999 is the world used by Electron's contextIsolation feature. Accepts values in the range 1..536870911.
• scripts WebSource[]
• userGesture Boolean (optional) - Default is false.
• callback Function (optional) - Called after script has been executed. Unless the frame is suspended (e.g. showing a modal alert), execution will be synchronous and the callback will be invoked before the method returns. For compatibility with an older version of this method, the error parameter is second.
  • result Any
  • error Error

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)

• worldId Integer - The ID of the world to run the javascript in, 0 is the default world, 999 is the world used by Electrons contextIsolation feature. Chrome extensions reserve the range of IDs in [1 << 20, 1 << 29). You can provide any integer here.
• info Object
  • securityOrigin String (optional) - Security origin for the isolated world.
  • csp String (optional) - Content Security Policy for the isolated world.
  • name String (optional) - Name for isolated world. Useful in devtools.

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:

• images MemoryUsageDetails
• scripts MemoryUsageDetails
• cssStyleSheets MemoryUsageDetails
• xslStyleSheets MemoryUsageDetails
• fonts MemoryUsageDetails
• other MemoryUsageDetails

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)

• selector String - CSS selector for a frame element.

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)

• name String

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)

• routingId Integer - An Integer representing the unique frame id in the current renderer process. Routing IDs can be retrieved from WebFrame instances (webFrame.routingId) and are also passed by frame specific WebContents navigation events (e.g. did-frame-navigate)

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

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.