Electon Postman 📬

Electron Postman is an easy-to-use wrapper around Electron's built-in IPC library.

Features:

• Similar IPC methods in main and renderer process
• Easy and direct window-to-window communication
• Integrates smoothly in nodeIntegration disabled and contextIsolation enabled BrowserWindows
• Allows invoke calls not only from renderer to main process, but also the other way around

Example

You can register windows on creation. The window registration is broadcasted to all other windows automatically.

// main.js
ipcMain.registerBrowserWindow('window-a', windowA);

From now on, windows can communicate directly with each other.

// windowB.js
ipcRenderer.sendTo('window-a', 'channel-name', args);

If you implement Electron's security recommandations and have disabled node integration and enabled context isolation for browser windows, you can expose Electron Postman easily via a preload script.

// preload.js
ipcRenderer.exposeInMainWorld('ipc');

// windowA.js
window.ipc.invokeTo('window-b').then((result) => console.log(result));

Installation

Yarn:

yarn add electron-postman

npm:

npm install electron-postman

Usage

1. Register a window before its content is loaded.

// main.js
const { ipcMain } = require('electron-postman');
// ...
const mainWindow = createMainWindow();
ipcMain.registerBrowserWindow('main-window', mainWindow);
mainWindow.loadFile(path);

2. (Optional) If using a preload script, expose the API to the renderer process.

// preload.js
const { ipcRenderer } = require('electron-postman');
ipcRenderer.exposeInMainWorld('ipc');

3. Send, invoke, handle and receive messages in main and in renderer processes.

API

ipcMain

ipcMain.registerBrowserWindow(windowName, browserWindow)

• windowName String
• browserWindow BrowserWindow

Registers the window and is made known with all other existing windows.

ipcMain.sendTo(windowName, channel, ...args)

• windowName String
• channel String
• ...args any[]

Send an asynchronous message to the renderer process via channel, along with arguments. Requires that windowName is a registered window. The renderer process can handle the message by listening to channel.

ipcMain.on(windowName, channel, listener)

• windowName String
• channel String
• listener Function
  • ...args any[]

Listen to messages on channel from window windowName. Requires that windowName is a registered window.

ipcMain.once(windowName, channel, listener)

• windowName String
• channel String
• listener Function
  • ...args any[]

Same as ipcMain.on, but listener is removed once a message on channel was received.

ipcMain.invokeTo(windowName, channel, ...args)

• windowName String
• channel String
• ...args any[]

Returns Promise<any> - Resolves with the response from the other process.

Send a message to windowName via channel and expect a result asynchronously. The other process should listen for channel with ipcMain.handle() or ipcRenderer.handle() respectively.

ipcMain.handle(windowName, channel, listener)

• windowName String
• channel String
• listener Function
  • ...args any[]

Adds a handler for an invokeable IPC. This handler will be called whenever a renderer calls ipcRenderer.invoke(channel, ...args) or ipcRenderer.invokeTo('main', channel, ...args.

If listener returns a Promise, the eventual result of the promise will be returned as a reply to the remote caller. Otherwise, the return value of the listener will be used as the value of the reply.

ipcMain.handleOnce(windowName, channel, listener)

• windowName String
• channel String
• listener Function
  • ...args any[]

Same as ipcMain.handle, but handler is removed once an invoke call was handled.

ipcMain.removeAllListeners(windowName, channel)

• windowName String
• channel String

Removes all listeners registered on windowName and channel.

ipcMain.removeHandler(windowName, channel)

• windowName String
• channel String

Removes handler, registered on windowame and channel.

ipcRenderer

Each process is addressed with its process name (processName). For a renderer process, its process name is the registered window name (renderer-to-renderer communication), the main process has the process name 'main' (renderer-to-main communication).

ipcRenderer.exposeInMainWorld(apiKey)

• apiKey String

Exposes the IPC renderer API to context isolated renderer process. Works only, if contextIsolation is enabled for that window. Uses Electron's contextBridge API.

ipcRenderer.send(channel, ...args)

• channel String
• ...args any[]

Equivalent to ipcRenderer.sendTo('main', channel, ...args).

ipcRenderer.sendTo(processName, channel, ...args)

• processName String
• channel String
• ...args any[]

Send an asynchronous message to the process registered as processName via channel, along with arguments. The receiving process can handle the message by listening to channel.

ipcRenderer.on(processName, channel, listener)

• processName String
• channel String
• listener Function
  • ...args any[]

Listen to messages on channel from process processName.

ipcRenderer.once(processName, channel, listener)

• processName String
• channel String
• listener Function
  • ...args any[]

Same as ipcMain.on, but listener is removed once a message on channel was received.

ipcRenderer.invoke(channel, ...args)

• processName String
• channel String
• ...args any[]

Equivalent to ipcRenderer.invokeTo('main', channel, ...args).

ipcRenderer.invokeTo(processName, channel, ...args)

• processName String
• channel String
• ...args any[]

Returns Promise<any> - Resolves with the response from the other process.

Send a message to windowName via channel and expect a result asynchronously. The other process should listen for channel with ipcMain.handle() or ipcRenderer.handle() respectively.

ipcRenderer.handle(processName, channel, listener)

• processName String
• channel String
• listener Function
  • ...args any[]

Adds a handler for an invokeable IPC. This handler will be called whenever a process calls .invoke('this-window-name', channel, ...args).

If listener returns a Promise, the eventual result of the promise will be returned as a reply to the remote caller. Otherwise, the return value of the listener will be used as the value of the reply.

ipcRenderer.handleOnce(processName, channel, listener)

• processName String
• channel String
• listener Function
  • ...args any[]

Same as ipcRenderer.handle, but handler is removed once an invoke call was handled.

ipcRenderer.removeAllListeners(processName, channel)

• processName String
• channel String

Removes all listeners registered on processName and channel.

ipcRenderer.removeHandler(processName, channel)

• processName String
• channel String

Removes handler, registered on processName and channel.