85 lines
2.6 KiB
Markdown
85 lines
2.6 KiB
Markdown
# ipcRenderer
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> Communicate asynchronously from a renderer process to the main process.
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Process: [Renderer](../tutorial/quick-start.md#renderer-process)
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The `ipcRenderer` module is an instance of the
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[EventEmitter](https://nodejs.org/api/events.html#events_class_eventemitter) class. 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:
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### `ipcRenderer.on(channel, listener)`
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* `channel` String
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* `listener` Function
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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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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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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 (optional)
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Removes all listeners, or those of the specified `channel`.
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## Sending Messages
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The `ipcRenderer` module has the following methods for sending messages:
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### `ipcRenderer.send(channel[, arg1][, arg2][, ...])`
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* `channel` String
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* `arg` (optional)
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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 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` module.
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### `ipcRenderer.sendSync(channel[, arg1][, arg2][, ...])`
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* `channel` String
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* `arg` (optional)
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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` 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.sendToHost(channel[, arg1][, arg2][, ...])`
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* `channel` String
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* `arg` (optional)
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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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