electron/docs/api/ipc-renderer.md

ipcRenderer

Communicate asynchronously from a renderer process to the main process.

Process: Renderer

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.

Methods

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

ipcRenderer.on(channel, listener)

• channel String
• listener Function

Listens to channel, when a new message arrives listener would be called with listener(event, args...).

ipcRenderer.once(channel, listener)

• channel String
• listener Function

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

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[, arg1][, arg2][, ...])

• channel String
• ...args any[]

Send a message to the main process asynchronously via channel, you can also send arbitrary arguments. Arguments will be serialized in JSON internally and hence no functions or prototype chain will be included.

The main process handles it by listening for channel with ipcMain module.

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

• channel String
• ...args any[]

Returns any - The value sent back by the ipcMain handler.

Send a message to the main process synchronously via channel, you can also send arbitrary arguments. Arguments will be serialized in JSON internally and hence no functions or prototype chain will be included.

The main process handles it by listening for channel with ipcMain module, 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.sendTo(webContentsId, channel, [, arg1][, arg2][, ...])

• webContentsId Number
• channel String
• ...args any[]

Sends a message to a window with webContentsId via channel.

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

• 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 event object passed to the callback has the following methods:

event.senderId

Returns the webContents.id that sent the message, you can call event.sender.sendTo(event.senderId, ...) to reply to the message, see ipcRenderer.sendTo for more information. This only applies to messages sent from a different renderer. Messages sent directly from the main process set event.senderId to 0.