How to call a function in another script from main.js in electron

My main.js file in my electron program has a small context menu that is opened when right-clicking the tray icon, like so:

let menuTarea = [
    {
        label: "Open window",
        click:  function(){ win.show(); }
    },
    {
        label: "**omitted**",
        click:  function(){ shell.openExternal("**omitted**"); }
    },
    {
        label: "Close completely",
        click:  function(){ app.quit(); }
    }
]

I would like one of the menu buttons to call a function that is in another script.js file, which is running in the background as it's referenced by the index.html in the main window. How can I do this?

Solution

You just have to require the script you want to use in index.html, then call it from main.js either by

executeJavaScript on the page
or using ipc communication

A full example could be:

main.js

const { app, Menu, Tray, BrowserWindow } = require('electron')
const path = require('path')

let tray = null
let win = null
app.on('ready', () => {
  win = new BrowserWindow({
    show: false
  })
  win.loadURL(path.join(__dirname, 'index.html'))
  tray = new Tray('test.png')
  const contextMenu = Menu.buildFromTemplate([
    {label: "Open window", click: () => { win.show() }},
    {label: "Close completely", click: () => { app.quit() }},
    // call required function
    {
      label: "Call function",
      click: () => {
        const text = 'asdasdasd'
        // #1
        win.webContents.send('call-foo', text)
        // #2
        win.webContents.executeJavaScript(`
          foo('${text}')
        `)
      }
    }
  ])
  tray.setContextMenu(contextMenu)
})

index.html

<html>
  <body>
    <script>
      const { foo } = require('./script.js')
      const { ipcRenderer } = require('electron')
      // For #1
      ipcRenderer.on('call-foo', (event, arg) => {
        foo(arg)
      })
    </script>
  </body>
</html>

script.js

module.exports = {
  foo: (text) => { console.log('foo says', text) }
}