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IPC ​

Novadesk uses a two-process model. The Main script (index.js) runs widget logic, while each UI script (e.g. ui.js) manages rendering. The IPC API lets these two layers exchange messages over named channels.

Table of Contents ​

INFO

ipcMain is only available in the Main script. ipcRenderer is only available in UI scripts.

IPC Message Object ​

Every listener receives an event object as its first argument with the following shape:

  • type (string): The channel name (defaults to "message").
  • payload (any): The data that was sent.
  • from (string): Origin of the message "main" or "ui".
  • to (string): Destination "main" or "ui".
  • channel (string): The channel the message was dispatched on.

ipcMain ​

Global object exposed in the Main script for communicating with UI scripts.

ipcMain.on(channel, listener) ​

Listens for messages sent from a UI script via ipcRenderer.send().

Parameters ​

  • channel (string): Non-empty channel name to listen on.
  • listener (function): Callback invoked as listener(event, payload).

Example ​

javascript
ipcMain.on("ui-ready", (event, payload) => {
  console.log("UI is ready:", JSON.stringify(payload));
});

ipcMain.handle(channel, handler) ​

Registers a handler that responds to ipcRenderer.invoke() calls. Only one handler can be active per channel registering again replaces the previous handler.

Parameters ​

  • channel (string): Non-empty channel name.
  • handler (function): Callback invoked as handler(event, payload). The return value is sent back to the invoking UI script.

Example ​

javascript
ipcMain.handle("get-config", (event, payload) => {
  return { theme: "dark", version: 2 };
});

ipcMain.send(channel, payload) ​

Sends a message from the Main script to all UI listeners registered on the given channel.

Parameters ​

  • channel (string): Channel name.
  • payload (any, optional): Data to send.

Example ​

javascript
ipcMain.send("main-ready", { ts: Date.now(), note: "hello from main" });

ipcRenderer ​

Global object exposed in UI scripts for communicating with the Main script.

ipcRenderer.on(channel, listener) ​

Listens for messages sent from the Main script via ipcMain.send().

Parameters ​

  • channel (string): Non-empty channel name to listen on.
  • listener (function): Callback invoked as listener(event, payload).

Example ​

javascript
ipcRenderer.on("main-ready", (event, payload) => {
  console.log("Main says:", JSON.stringify(payload));
  ui.setElementProperties("status", { text: "main-ready" });
});

ipcRenderer.send(channel, payload) ​

Sends a message from a UI script to all Main listeners registered on the given channel.

Parameters ​

  • channel (string): Channel name.
  • payload (any, optional): Data to send.

Example ​

javascript
ipcRenderer.send("ui-ready", { ts: Date.now() });

ipcRenderer.invoke(channel, payload) ​

Sends a request to the Main script and returns the result synchronously. The Main script must have a handler registered via ipcMain.handle() for the same channel; otherwise a ReferenceError is thrown.

Parameters ​

  • channel (string): Non-empty channel name.
  • payload (any, optional): Data to send.

Return Value ​

The value returned by the corresponding ipcMain.handle() handler.

Example ​

javascript
ipcMain.handle("get-config", (event, payload) => {
  return { theme: "dark" };
});

Full Example ​

javascript
import { widgetWindow } from 'novadesk';

ipcMain.on("ui-ready", (event, payload) => {
  console.log("[main] UI ready:", JSON.stringify(payload));
});

ipcMain.on("ui-ping", (event, payload) => {
  console.log("[main] ping from UI");
  ipcMain.send("main-pong", { ts: Date.now(), echo: payload });
});

ipcMain.handle("get-config", () => {
  return { theme: "dark", version: 1 };
});

const win = new widgetWindow({
  id: "demo",
  width: 400,
  height: 400,
  script: "ui.js",
  backgroundColor: "rgb(10,10,10)"
});

ipcMain.send("main-ready", { ts: Date.now() });