electron/docs/api/ipc-renderer.md

ipcRenderer

The ipcRenderer module is an instance of the EventEmitter class. 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 ipcMain for code examples.

Listening for Messages

The ipcRenderer module has the following method to listen for events:

ipcRenderer.on(channel, callback)

• channel String - The event name.
• callback Function

When the event occurs the callback is called with an event object and arbitrary arguments.

Once done listening for messages, if you longer want to activate this callback and for whatever reason can't merely stop sending messages on the channel, you can use:

ipcRenderer.removeListener(channel, callback)

• channel String - The event name.
• callback Function - The reference to the same function that you used for ipcRenderer.on(channel, callback)

Alternatively, if you don't have access to the same callback, you can use:

ipcRenderer.removeAllListeners(channel)

• channel String - The event name.

This has the expected effect of removing all handlers to this ipc channel.

Because of this class' inheritance from the EventEmitter node class, you can also use ipcRenderer.once(channel, callback) to fire handlers meant to occur only once, as in, they won't be activated after one call of callback

Sending Messages

The ipcRenderer module has the following methods for sending messages:

ipcRenderer.send(channel[, arg1][, arg2][, ...])

• channel String - The event name.
• arg (optional)

Send an event to the main process asynchronously via a channel, you can also send arbitrary arguments. The main process handles it by listening for the channel event with ipcMain.

ipcRenderer.sendSync(channel[, arg1][, arg2][, ...])

• channel String - The event name.
• arg (optional)

Send an event to the main process synchronously via a channel, you can also send arbitrary arguments.

The main process handles it by listening for the channel event with ipcMain and replies by setting event.returnValue.

Note: Sending a synchronous message will block the whole renderer process, unless you know what you are doing you should never use it.

ipcRenderer.sendToHost(channel[, arg1][, arg2][, ...])

• channel String - The event name.
• arg (optional)

Like ipcRenderer.send but the event will be sent to the <webview> element in the host page instead of the main process.