electron/docs/api/ipc-browser.md

ipc (browser)

Handles asynchronous and synchronous message sent from web page.

The messages sent from web page would be emitted to this module, the event name is the channel when sending message. To reply a synchronous message, you need to set event.returnValue, to send an asynchronous back to the sender, you can use event.sender.send(...).

It's also possible to send messages from browser side to web pages, see WebContents.send for more.

An example of sending and handling messages:

// In browser.
var ipc = require('ipc');
ipc.on('asynchronous-message', function(event, arg) {
  console.log(arg);  // prints "ping"
  event.sender.send('asynchronous-reply', 'pong');
});

ipc.on('synchronous-message', function(event, arg) {
  console.log(arg);  // prints "ping"
  event.returnValue = 'pong'.
});

// In web page.
var ipc = require('ipc');
console.log(ipc.sendSync('synchronous-message', 'ping')); // prints "pong"

ipc.on('asynchronous-reply', function(arg) {
  console.log(arg); // prints "pong"
});
ipc.send('asynchronous-message', 'ping');

Class: Event

Event.returnValue

Assign to this to return an value to synchronous messages.

Event.sender

The WebContents of the web page that has sent the message.