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ipc-renderer.md
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---
title: "ipcRenderer"
description: "Communicate asynchronously from a renderer process to the main process."
slug: ipc-renderer
hide_title: false
---
# ipcRenderer
> Communicate asynchronously from a renderer process to the main process.
Process: [Renderer](../glossary.md#renderer-process)
The `ipcRenderer` module is an [EventEmitter][event-emitter]. It provides a few
methods so you can send synchronous and asynchronous messages from the render
process (web page) to the main process. You can also receive replies from the
main process.
See [IPC tutorial](../tutorial/ipc.md) for code examples.
## Methods
The `ipcRenderer` module has the following method to listen for events and send messages:
### `ipcRenderer.on(channel, listener)`
* `channel` string
* `listener` Function
* `event` IpcRendererEvent
* `...args` any[]
Listens to `channel`, when a new message arrives `listener` would be called with
`listener(event, args...)`.
### `ipcRenderer.once(channel, listener)`
* `channel` string
* `listener` Function
* `event` IpcRendererEvent
* `...args` any[]
Adds a one time `listener` function for the event. This `listener` is invoked
only the next time a message is sent to `channel`, after which it is removed.
### `ipcRenderer.removeListener(channel, listener)`
* `channel` string
* `listener` Function
* `...args` any[]
Removes the specified `listener` from the listener array for the specified
`channel`.
### `ipcRenderer.removeAllListeners(channel)`
* `channel` string
Removes all listeners, or those of the specified `channel`.
### `ipcRenderer.send(channel, ...args)`
* `channel` string
* `...args` any[]
Send an asynchronous message to the main process via `channel`, along with
arguments. Arguments will be serialized with the [Structured Clone
Algorithm][SCA], just like [`window.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 will throw an exception.
>
> Since the main process does not have support for DOM objects such as
> `ImageBitmap`, `File`, `DOMMatrix` and so on, such objects cannot be sent over
> Electron's IPC to the main process, as the main process would have no way to decode
> them. Attempting to send such objects over IPC will result in an error.
The main process handles it by listening for `channel` with the
[`ipcMain`](./ipc-main.md) module.
If you need to transfer a [`MessagePort`][] to the main process, use [`ipcRenderer.postMessage`](#ipcrendererpostmessagechannel-message-transfer).
If you want to receive a single response from the main process, like the result of a method call, consider using [`ipcRenderer.invoke`](#ipcrendererinvokechannel-args).
### `ipcRenderer.invoke(channel, ...args)`
* `channel` string
* `...args` any[]
Returns `Promise<any>` - Resolves with the response from the main process.
Send a message to the main process via `channel` and expect a result
asynchronously. Arguments will be serialized with the [Structured Clone
Algorithm][SCA], just like [`window.postMessage`][], so prototype chains will not be
included. Sending Functions, Promises, Symbols, WeakMaps, or WeakSets will
throw an exception.
The main process should listen for `channel` with
[`ipcMain.handle()`](./ipc-main.md#ipcmainhandlechannel-listener).
For example:
```javascript @ts-type={someArgument:unknown} @ts-type={doSomeWork:(arg:unknown)=>Promise<unknown>}
// Renderer process
ipcRenderer.invoke('some-name', someArgument).then((result) => {
// ...
})
// Main process
ipcMain.handle('some-name', async (event, someArgument) => {
const result = await doSomeWork(someArgument)
return result
})
```
If you need to transfer a [`MessagePort`][] to the main process, use [`ipcRenderer.postMessage`](#ipcrendererpostmessagechannel-message-transfer).
If you do not need a response to the message, consider using [`ipcRenderer.send`](#ipcrenderersendchannel-args).
> **Note**
> Sending non-standard JavaScript types such as DOM objects or
> special Electron objects will throw an exception.
>
> Since the main process does not have support for DOM objects such as
> `ImageBitmap`, `File`, `DOMMatrix` and so on, such objects cannot be sent over
> Electron's IPC to the main process, as the main process would have no way to decode
> them. Attempting to send such objects over IPC will result in an error.
> **Note**
> If the handler in the main process throws an error,
> the promise returned by `invoke` will reject.
> However, the `Error` object in the renderer process
> will not be the same as the one thrown in the main process.
### `ipcRenderer.sendSync(channel, ...args)`
* `channel` string
* `...args` any[]
Returns `any` - The value sent back by the [`ipcMain`](./ipc-main.md) handler.
Send a message to the main process via `channel` and expect a result
synchronously. Arguments will be serialized with the [Structured Clone
Algorithm][SCA], just like [`window.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 will throw an exception.
>
> Since the main process does not have support for DOM objects such as
> `ImageBitmap`, `File`, `DOMMatrix` and so on, such objects cannot be sent over
> Electron's IPC to the main process, as the main process would have no way to decode
> them. Attempting to send such objects over IPC will result in an error.
The main process handles it by listening for `channel` with [`ipcMain`](./ipc-main.md) module,
and replies by setting `event.returnValue`.
> :warning: **WARNING**: Sending a synchronous message will block the whole
> renderer process until the reply is received, so use this method only as a
> last resort. It's much better to use the asynchronous version,
> [`invoke()`](./ipc-renderer.md#ipcrendererinvokechannel-args).
### `ipcRenderer.postMessage(channel, message, [transfer])`
* `channel` string
* `message` any
* `transfer` MessagePort[] (optional)
Send a message to the main process, optionally transferring ownership of zero
or more [`MessagePort`][] objects.
The transferred `MessagePort` objects will be available in the main process as
[`MessagePortMain`](./message-port-main.md) objects by accessing the `ports`
property of the emitted event.
For example:
```js
// Renderer process
const { port1, port2 } = new MessageChannel()
ipcRenderer.postMessage('port', { message: 'hello' }, [port1])
// Main process
ipcMain.on('port', (e, msg) => {
const [port] = e.ports
// ...
})
```
For more information on using `MessagePort` and `MessageChannel`, see the [MDN
documentation](https://developer.mozilla.org/en-US/docs/Web/API/MessageChannel).
### `ipcRenderer.sendTo(webContentsId, channel, ...args)`
* `webContentsId` number
* `channel` string
* `...args` any[]
Sends a message to a window with `webContentsId` via `channel`.
### `ipcRenderer.sendToHost(channel, ...args)`
* `channel` string
* `...args` any[]
Like `ipcRenderer.send` but the event will be sent to the `<webview>` element in
the host page instead of the main process.
## Event object
The documentation for the `event` object passed to the `callback` can be found
in the [`ipc-renderer-event`](./structures/ipc-renderer-event.md) structure docs.
[event-emitter]: https://nodejs.org/api/events.html#events_class_eventemitter
[SCA]: https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm
[`window.postMessage`]: https://developer.mozilla.org/en-US/docs/Web/API/Window/postMessage
[`MessagePort`]: https://developer.mozilla.org/en-US/docs/Web/API/MessagePort