131 lines
3.8 KiB
Markdown
131 lines
3.8 KiB
Markdown
# ipcRenderer
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> Communicate asynchronously from a renderer process to the main process.
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Process: [Renderer](../glossary.md#renderer-process)
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The `ipcRenderer` module is an [EventEmitter][event-emitter]. It provides a few
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methods so you can send synchronous and asynchronous messages from the render
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process (web page) to the main process. You can also receive replies from the
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main process.
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See [ipcMain](ipc-main.md) for code examples.
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## Methods
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The `ipcRenderer` module has the following method to listen for events and send messages:
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### `ipcRenderer.on(channel, listener)`
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* `channel` String
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* `listener` Function
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* `event` IpcRendererEvent
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* `...args` any[]
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Listens to `channel`, when a new message arrives `listener` would be called with
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`listener(event, args...)`.
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### `ipcRenderer.once(channel, listener)`
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* `channel` String
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* `listener` Function
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* `event` IpcRendererEvent
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* `...args` any[]
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Adds a one time `listener` function for the event. This `listener` is invoked
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only the next time a message is sent to `channel`, after which it is removed.
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### `ipcRenderer.removeListener(channel, listener)`
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* `channel` String
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* `listener` Function
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* `...args` any[]
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Removes the specified `listener` from the listener array for the specified
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`channel`.
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### `ipcRenderer.removeAllListeners(channel)`
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* `channel` String
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Removes all listeners, or those of the specified `channel`.
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### `ipcRenderer.send(channel, ...args)`
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* `channel` String
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* `...args` any[]
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Send a message to the main process asynchronously via `channel`, you can also
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send arbitrary arguments. Arguments will be serialized as JSON internally and
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hence no functions or prototype chain will be included.
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The main process handles it by listening for `channel` with the
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[`ipcMain`](ipc-main.md) module.
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### `ipcRenderer.invoke(channel, ...args)`
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* `channel` String
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* `...args` any[]
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Returns `Promise<any>` - Resolves with the response from the main process.
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Send a message to the main process asynchronously via `channel` and expect an
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asynchronous result. Arguments will be serialized as JSON internally and
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hence no functions or prototype chain will be included.
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The main process should listen for `channel` with
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[`ipcMain.handle()`](ipc-main.md#ipcmainhandlechannel-listener).
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For example:
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```javascript
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// Renderer process
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ipcRenderer.invoke('some-name', someArgument).then((result) => {
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// ...
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})
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// Main process
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ipcMain.handle('some-name', async (event, someArgument) => {
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const result = await doSomeWork(someArgument)
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return result
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})
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```
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### `ipcRenderer.sendSync(channel, ...args)`
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* `channel` String
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* `...args` any[]
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Returns `any` - The value sent back by the [`ipcMain`](ipc-main.md) handler.
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Send a message to the main process synchronously via `channel`, you can also
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send arbitrary arguments. Arguments will be serialized in JSON internally and
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hence no functions or prototype chain will be included.
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The main process handles it by listening for `channel` with [`ipcMain`](ipc-main.md) module,
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and replies by setting `event.returnValue`.
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**Note:** Sending a synchronous message will block the whole renderer process,
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unless you know what you are doing you should never use it.
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### `ipcRenderer.sendTo(webContentsId, channel, ...args)`
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* `webContentsId` Number
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* `channel` String
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* `...args` any[]
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Sends a message to a window with `webContentsId` via `channel`.
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### `ipcRenderer.sendToHost(channel, ...args)`
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* `channel` String
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* `...args` any[]
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Like `ipcRenderer.send` but the event will be sent to the `<webview>` element in
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the host page instead of the main process.
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## Event object
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The documentation for the `event` object passed to the `callback` can be found
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in the [`ipc-renderer-event`](structures/ipc-renderer-event.md) structure docs.
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[event-emitter]: https://nodejs.org/api/events.html#events_class_eventemitter
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