ipcMain
ipcMain
Communicate asynchronously from the main process to renderer processes.
Process: Main
The ipcMain
module is an instance of the EventEmitter class. When used in the main process, it handles asynchronous and synchronous messages sent from a renderer process (web page). Messages sent from a renderer will be emitted to this module.
Sending Messages
It is also possible to send messages from the main process to the renderer process, see webContents.send for more information.
- When sending a message, the event name is the
channel
. - To reply to a synchronous message, you need to set
event.returnValue
. - To send an asynchronous message back to the sender, you can use
event.sender.send(...)
.
An example of sending and handling messages between the render and main processes:
// In main process. const {ipcMain} = require('electron') ipcMain.on('asynchronous-message', (event, arg) => { console.log(arg) // prints "ping" event.sender.send('asynchronous-reply', 'pong') }) ipcMain.on('synchronous-message', (event, arg) => { console.log(arg) // prints "ping" event.returnValue = 'pong' })
// In renderer process (web page). const {ipcRenderer} = require('electron') console.log(ipcRenderer.sendSync('synchronous-message', 'ping')) // prints "pong" ipcRenderer.on('asynchronous-reply', (event, arg) => { console.log(arg) // prints "pong" }) ipcRenderer.send('asynchronous-message', 'ping')
Methods
The ipcMain
module has the following method to listen for events:
ipcMain.on(channel, listener)
-
channel
String -
listener
Function
Listens to channel
, when a new message arrives listener
would be called with listener(event, args...)
.
ipcMain.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.
ipcMain.removeListener(channel, listener)
-
channel
String -
listener
Function
Removes the specified listener
from the listener array for the specified channel
.
ipcMain.removeAllListeners([channel])
-
channel
String (optional)
Removes all listeners, or those of the specified channel
.
Event object
The event
object passed to the callback
has the following methods:
event.returnValue
Set this to the value to be returned in a synchronous message.
event.sender
Returns the webContents
that sent the message, you can call event.sender.send
to reply to the asynchronous message, see webContents.send for more information.
© 2013–2017 GitHub Inc.
Licensed under the MIT license.
https://electron.atom.io/docs/api/ipc-main/