electron/docs/api/breaking-changes.md

# Breaking Changes

Breaking changes will be documented here, and deprecation warnings added to JS code where possible, at least [one major version](../tutorial/electron-versioning.md#semver) before the change is made.

## `FIXME` comments

The `FIXME` string is used in code comments to denote things that should be fixed for future releases. See https://github.com/electron/electron/search?q=fixme

## Planned Breaking API Changes (9.0)

### `<webview>.getWebContents()`

This API, which was deprecated in Electron 8.0, is now removed.

```js
// Removed in Electron 9.0
webview.getWebContents()
// Replace with
const { remote } = require('electron')
remote.webContents.fromId(webview.getWebContentsId())
```

### `webFrame.setLayoutZoomLevelLimits()`

Chromium has removed support for changing the layout zoom level limits, and it
is beyond Electron's capacity to maintain it. The function was deprecated in
Electron 8.x, and has been removed in Electron 9.x. The layout zoom level limits
are now fixed at a minimum of 0.25 and a maximum of 5.0, as defined
[here](https://chromium.googlesource.com/chromium/src/+/938b37a6d2886bf8335fc7db792f1eb46c65b2ae/third_party/blink/common/page/page_zoom.cc#11).

### Sending non-JS objects over IPC now throws an exception

In Electron 8.0, IPC was changed to use the Structured Clone Algorithm,
bringing significant performance improvements. To help ease the transition, the
old IPC serialization algorithm was kept and used for some objects that aren't
serializable with Structured Clone. In particular, DOM objects (e.g. `Element`,
`Location` and `DOMMatrix`), Node.js objects backed by C++ classes (e.g.
`process.env`, some members of `Stream`), and Electron objects backed by C++
classes (e.g. `WebContents`, `BrowserWindow` and `WebFrame`) are not
serializable with Structured Clone. Whenever the old algorithm was invoked, a
deprecation warning was printed.

In Electron 9.0, the old serialization algorithm has been removed, and sending
such non-serializable objects will now throw an "object could not be cloned"
error.

## Planned Breaking API Changes (8.0)

### Values sent over IPC are now serialized with Structured Clone Algorithm

The algorithm used to serialize objects sent over IPC (through
`ipcRenderer.send`, `ipcRenderer.sendSync`, `WebContents.send` and related
methods) has been switched from a custom algorithm to V8's built-in [Structured
Clone Algorithm][SCA], the same algorithm used to serialize messages for
`postMessage`. This brings about a 2x performance improvement for large
messages, but also brings some breaking changes in behavior.

- Sending Functions, Promises, WeakMaps, WeakSets, or objects containing any
  such values, over IPC will now throw an exception, instead of silently
  converting the functions to `undefined`.
```js
// Previously:
ipcRenderer.send('channel', { value: 3, someFunction: () => {} })
// => results in { value: 3 } arriving in the main process

// From Electron 8:
ipcRenderer.send('channel', { value: 3, someFunction: () => {} })
// => throws Error("() => {} could not be cloned.")
```
- `NaN`, `Infinity` and `-Infinity` will now be correctly serialized, instead
  of being converted to `null`.
- Objects containing cyclic references will now be correctly serialized,
  instead of being converted to `null`.
- `Set`, `Map`, `Error` and `RegExp` values will be correctly serialized,
  instead of being converted to `{}`.
- `BigInt` values will be correctly serialized, instead of being converted to
  `null`.
- Sparse arrays will be serialized as such, instead of being converted to dense
  arrays with `null`s.
- `Date` objects will be transferred as `Date` objects, instead of being
  converted to their ISO string representation.
- Typed Arrays (such as `Uint8Array`, `Uint16Array`, `Uint32Array` and so on)
  will be transferred as such, instead of being converted to Node.js `Buffer`.
- Node.js `Buffer` objects will be transferred as `Uint8Array`s. You can
  convert a `Uint8Array` back to a Node.js `Buffer` by wrapping the underlying
  `ArrayBuffer`:
```js
Buffer.from(value.buffer, value.byteOffset, value.byteLength)
```

Sending any objects that aren't native JS types, such as DOM objects (e.g.
`Element`, `Location`, `DOMMatrix`), Node.js objects (e.g. `process.env`,
`Stream`), or Electron objects (e.g. `WebContents`, `BrowserWindow`,
`WebFrame`) is deprecated. In Electron 8, these objects will be serialized as
before with a DeprecationWarning message, but starting in Electron 9, sending
these kinds of objects will throw a 'could not be cloned' error.

[SCA]: https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm

### `<webview>.getWebContents()`

This API is implemented using the `remote` module, which has both performance
and security implications. Therefore its usage should be explicit.

```js
// Deprecated
webview.getWebContents()
// Replace with
const { remote } = require('electron')
remote.webContents.fromId(webview.getWebContentsId())
```

However, it is recommended to avoid using the `remote` module altogether.

```js
// main
const { ipcMain, webContents } = require('electron')

const getGuestForWebContents = (webContentsId, contents) => {
  const guest = webContents.fromId(webContentsId)
  if (!guest) {
    throw new Error(`Invalid webContentsId: ${webContentsId}`)
  }
  if (guest.hostWebContents !== contents) {
    throw new Error(`Access denied to webContents`)
  }
  return guest
}

ipcMain.handle('openDevTools', (event, webContentsId) => {
  const guest = getGuestForWebContents(webContentsId, event.sender)
  guest.openDevTools()
})

// renderer
const { ipcRenderer } = require('electron')

ipcRenderer.invoke('openDevTools', webview.getWebContentsId())
```

### `webFrame.setLayoutZoomLevelLimits()`

Chromium has removed support for changing the layout zoom level limits, and it
is beyond Electron's capacity to maintain it. The function will emit a warning
in Electron 8.x, and cease to exist in Electron 9.x. The layout zoom level
limits are now fixed at a minimum of 0.25 and a maximum of 5.0, as defined
[here](https://chromium.googlesource.com/chromium/src/+/938b37a6d2886bf8335fc7db792f1eb46c65b2ae/third_party/blink/common/page/page_zoom.cc#11).

## Planned Breaking API Changes (7.0)

### Node Headers URL

This is the URL specified as `disturl` in a `.npmrc` file or as the `--dist-url`
command line flag when building native Node modules.  Both will be supported for
the foreseeable future but it is recommended that you switch.

Deprecated: https://atom.io/download/electron

Replace with: https://electronjs.org/headers

### `session.clearAuthCache(options)`

The `session.clearAuthCache` API no longer accepts options for what to clear, and instead unconditionally clears the whole cache.

```js
// Deprecated
session.clearAuthCache({ type: 'password' })
// Replace with
session.clearAuthCache()
```

### `powerMonitor.querySystemIdleState`

```js
// Removed in Electron 7.0
powerMonitor.querySystemIdleState(threshold, callback)
// Replace with synchronous API
const idleState = getSystemIdleState(threshold)
```

### `powerMonitor.querySystemIdleTime`

```js
// Removed in Electron 7.0
powerMonitor.querySystemIdleTime(callback)
// Replace with synchronous API
const idleTime = getSystemIdleTime()
```

### webFrame Isolated World APIs

```js
// Removed in Electron 7.0
webFrame.setIsolatedWorldContentSecurityPolicy(worldId, csp)
webFrame.setIsolatedWorldHumanReadableName(worldId, name)
webFrame.setIsolatedWorldSecurityOrigin(worldId, securityOrigin)
// Replace with
webFrame.setIsolatedWorldInfo(
  worldId,
  {
    securityOrigin: 'some_origin',
    name: 'human_readable_name',
    csp: 'content_security_policy'
  })
```

### Removal of deprecated `marked` property on getBlinkMemoryInfo

This property was removed in Chromium 77, and as such is no longer available.

### `webkitdirectory` attribute for `<input type="file"/>`

The `webkitdirectory` property on HTML file inputs allows them to select folders.
Previous versions of Electron had an incorrect implementation where the `event.target.files`
of the input returned a `FileList` that returned one `File` corresponding to the selected folder.

As of Electron 7, that `FileList` is now list of all files contained within
the folder, similarly to Chrome, Firefox, and Edge
([link to MDN docs](https://developer.mozilla.org/en-US/docs/Web/API/HTMLInputElement/webkitdirectory)).

As an illustration, take a folder with this structure:
```console
folder
├── file1
├── file2
└── file3
```

In Electron <=6, this would return a `FileList` with a `File` object for:
```console
path/to/folder
```

In Electron 7, this now returns a `FileList` with a `File` object for:
```console
/path/to/folder/file3
/path/to/folder/file2
/path/to/folder/file1
```

Note that `webkitdirectory` no longer exposes the path to the selected folder.
If you require the path to the selected folder rather than the folder contents,
see the `dialog.showOpenDialog` API ([link](https://github.com/electron/electron/blob/master/docs/api/dialog.md#dialogshowopendialogbrowserwindow-options)).
## Planned Breaking API Changes (6.0)

### `win.setMenu(null)`

```js
// Deprecated
win.setMenu(null)
// Replace with
win.removeMenu()
```

### `contentTracing.getTraceBufferUsage()`

```js
// Deprecated
contentTracing.getTraceBufferUsage((percentage, value) => {
  // do something
})
// Replace with
contentTracing.getTraceBufferUsage().then(infoObject => {
  // infoObject has percentage and value fields
})
```

### `electron.screen` in renderer process

```js
// Deprecated
require('electron').screen
// Replace with
require('electron').remote.screen
```

### `require` in sandboxed renderers

```js
// Deprecated
require('child_process')
// Replace with
require('electron').remote.require('child_process')

// Deprecated
require('fs')
// Replace with
require('electron').remote.require('fs')

// Deprecated
require('os')
// Replace with
require('electron').remote.require('os')

// Deprecated
require('path')
// Replace with
require('electron').remote.require('path')
```

### `powerMonitor.querySystemIdleState`

```js
// Deprecated
powerMonitor.querySystemIdleState(threshold, callback)
// Replace with synchronous API
const idleState = getSystemIdleState(threshold)
```

### `powerMonitor.querySystemIdleTime`

```js
// Deprecated
powerMonitor.querySystemIdleTime(callback)
// Replace with synchronous API
const idleTime = getSystemIdleTime()
```

### `app.enableMixedSandbox`

```js
// Deprecated
app.enableMixedSandbox()
```

Mixed-sandbox mode is now enabled by default.

### `Tray`

Under macOS Catalina our former Tray implementation breaks.
Apple's native substitute doesn't support changing the highlighting behavior.

```js
// Deprecated
tray.setHighlightMode(mode)
// API will be removed in v7.0 without replacement.
```

## Planned Breaking API Changes (5.0)

### `new BrowserWindow({ webPreferences })`

The following `webPreferences` option default values are deprecated in favor of the new defaults listed below.

| Property | Deprecated Default | New Default |
|----------|--------------------|-------------|
| `contextIsolation` | `false` | `true` |
| `nodeIntegration` | `true` | `false` |
| `webviewTag` | `nodeIntegration` if set else `true` | `false` |

E.g. Re-enabling the webviewTag

```js
const w = new BrowserWindow({
  webPreferences: {
    webviewTag: true
  }
})
```

### `nativeWindowOpen`

Child windows opened with the `nativeWindowOpen` option will always have Node.js integration disabled, unless `nodeIntegrationInSubFrames` is `true.

### Privileged Schemes Registration

Renderer process APIs `webFrame.setRegisterURLSchemeAsPrivileged` and `webFrame.registerURLSchemeAsBypassingCSP` as well as browser process API `protocol.registerStandardSchemes` have been removed.
A new API, `protocol.registerSchemesAsPrivileged` has been added and should be used for registering custom schemes with the required privileges. Custom schemes are required to be registered before app ready.

### webFrame Isolated World APIs

```js
// Deprecated
webFrame.setIsolatedWorldContentSecurityPolicy(worldId, csp)
webFrame.setIsolatedWorldHumanReadableName(worldId, name)
webFrame.setIsolatedWorldSecurityOrigin(worldId, securityOrigin)
// Replace with
webFrame.setIsolatedWorldInfo(
  worldId,
  {
    securityOrigin: 'some_origin',
    name: 'human_readable_name',
    csp: 'content_security_policy'
  })
```

## `webFrame.setSpellCheckProvider`
The `spellCheck` callback is now asynchronous, and `autoCorrectWord` parameter has been removed.
```js
// Deprecated
webFrame.setSpellCheckProvider('en-US', true, {
  spellCheck: (text) => {
    return !spellchecker.isMisspelled(text)
  }
})
// Replace with
webFrame.setSpellCheckProvider('en-US', {
  spellCheck: (words, callback) => {
    callback(words.filter(text => spellchecker.isMisspelled(text)))
  }
})
```

## Planned Breaking API Changes (4.0)

The following list includes the breaking API changes made in Electron 4.0.

### `app.makeSingleInstance`

```js
// Deprecated
app.makeSingleInstance((argv, cwd) => {
  /* ... */
})
// Replace with
app.requestSingleInstanceLock()
app.on('second-instance', (event, argv, cwd) => {
  /* ... */
})
```

### `app.releaseSingleInstance`

```js
// Deprecated
app.releaseSingleInstance()
// Replace with
app.releaseSingleInstanceLock()
```

### `app.getGPUInfo`

```js
app.getGPUInfo('complete')
// Now behaves the same with `basic` on macOS
app.getGPUInfo('basic')
```

### `win_delay_load_hook`

When building native modules for windows, the `win_delay_load_hook` variable in
the module's `binding.gyp` must be true (which is the default). If this hook is
not present, then the native module will fail to load on Windows, with an error
message like `Cannot find module`. See the [native module
guide](/docs/tutorial/using-native-node-modules.md) for more.

## Breaking API Changes (3.0)

The following list includes the breaking API changes in Electron 3.0.

### `app`

```js
// Deprecated
app.getAppMemoryInfo()
// Replace with
app.getAppMetrics()

// Deprecated
const metrics = app.getAppMetrics()
const { memory } = metrics[0] // Deprecated property
```

### `BrowserWindow`

```js
// Deprecated
let optionsA = { webPreferences: { blinkFeatures: '' } }
let windowA = new BrowserWindow(optionsA)
// Replace with
let optionsB = { webPreferences: { enableBlinkFeatures: '' } }
let windowB = new BrowserWindow(optionsB)

// Deprecated
window.on('app-command', (e, cmd) => {
  if (cmd === 'media-play_pause') {
    // do something
  }
})
// Replace with
window.on('app-command', (e, cmd) => {
  if (cmd === 'media-play-pause') {
    // do something
  }
})
```

### `clipboard`

```js
// Deprecated
clipboard.readRtf()
// Replace with
clipboard.readRTF()

// Deprecated
clipboard.writeRtf()
// Replace with
clipboard.writeRTF()

// Deprecated
clipboard.readHtml()
// Replace with
clipboard.readHTML()

// Deprecated
clipboard.writeHtml()
// Replace with
clipboard.writeHTML()
```

### `crashReporter`

```js
// Deprecated
crashReporter.start({
  companyName: 'Crashly',
  submitURL: 'https://crash.server.com',
  autoSubmit: true
})
// Replace with
crashReporter.start({
  companyName: 'Crashly',
  submitURL: 'https://crash.server.com',
  uploadToServer: true
})
```

### `nativeImage`

```js
// Deprecated
nativeImage.createFromBuffer(buffer, 1.0)
// Replace with
nativeImage.createFromBuffer(buffer, {
  scaleFactor: 1.0
})
```

### `process`

```js
// Deprecated
const info = process.getProcessMemoryInfo()
```

### `screen`

```js
// Deprecated
screen.getMenuBarHeight()
// Replace with
screen.getPrimaryDisplay().workArea
```

### `session`

```js
// Deprecated
ses.setCertificateVerifyProc((hostname, certificate, callback) => {
  callback(true)
})
// Replace with
ses.setCertificateVerifyProc((request, callback) => {
  callback(0)
})
```

### `Tray`

```js
// Deprecated
tray.setHighlightMode(true)
// Replace with
tray.setHighlightMode('on')

// Deprecated
tray.setHighlightMode(false)
// Replace with
tray.setHighlightMode('off')
```

### `webContents`

```js
// Deprecated
webContents.openDevTools({ detach: true })
// Replace with
webContents.openDevTools({ mode: 'detach' })

// Removed
webContents.setSize(options)
// There is no replacement for this API
```

### `webFrame`

```js
// Deprecated
webFrame.registerURLSchemeAsSecure('app')
// Replace with
protocol.registerStandardSchemes(['app'], { secure: true })

// Deprecated
webFrame.registerURLSchemeAsPrivileged('app', { secure: true })
// Replace with
protocol.registerStandardSchemes(['app'], { secure: true })
```

### `<webview>`

```js
// Removed
webview.setAttribute('disableguestresize', '')
// There is no replacement for this API

// Removed
webview.setAttribute('guestinstance', instanceId)
// There is no replacement for this API

// Keyboard listeners no longer work on webview tag
webview.onkeydown = () => { /* handler */ }
webview.onkeyup = () => { /* handler */ }
```

### Node Headers URL

This is the URL specified as `disturl` in a `.npmrc` file or as the `--dist-url`
command line flag when building native Node modules.

Deprecated: https://atom.io/download/atom-shell

Replace with: https://atom.io/download/electron

## Breaking API Changes (2.0)

The following list includes the breaking API changes made in Electron 2.0.

### `BrowserWindow`

```js
// Deprecated
let optionsA = { titleBarStyle: 'hidden-inset' }
let windowA = new BrowserWindow(optionsA)
// Replace with
let optionsB = { titleBarStyle: 'hiddenInset' }
let windowB = new BrowserWindow(optionsB)
```

### `menu`

```js
// Removed
menu.popup(browserWindow, 100, 200, 2)
// Replaced with
menu.popup(browserWindow, { x: 100, y: 200, positioningItem: 2 })
```

### `nativeImage`

```js
// Removed
nativeImage.toPng()
// Replaced with
nativeImage.toPNG()

// Removed
nativeImage.toJpeg()
// Replaced with
nativeImage.toJPEG()
```

### `process`

* `process.versions.electron` and `process.version.chrome` will be made
  read-only properties for consistency with the other `process.versions`
  properties set by Node.

### `webContents`

```js
// Removed
webContents.setZoomLevelLimits(1, 2)
// Replaced with
webContents.setVisualZoomLevelLimits(1, 2)
```

### `webFrame`

```js
// Removed
webFrame.setZoomLevelLimits(1, 2)
// Replaced with
webFrame.setVisualZoomLevelLimits(1, 2)
```

### `<webview>`

```js
// Removed
webview.setZoomLevelLimits(1, 2)
// Replaced with
webview.setVisualZoomLevelLimits(1, 2)
```

### Duplicate ARM Assets

Each Electron release includes two identical ARM builds with slightly different
filenames, like `electron-v1.7.3-linux-arm.zip` and
`electron-v1.7.3-linux-armv7l.zip`. The asset with the `v7l` prefix was added
to clarify to users which ARM version it supports, and to disambiguate it from
future armv6l and arm64 assets that may be produced.

The file _without the prefix_ is still being published to avoid breaking any
setups that may be consuming it. Starting at 2.0, the unprefixed file will
no longer be published.

For details, see
[6986](https://github.com/electron/electron/pull/6986)
and
[7189](https://github.com/electron/electron/pull/7189).