electron/spec/fixtures/api/exit-closes-all-windows-app/main.js

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

const windows = []

function createWindow (id) {
  const window = new BrowserWindow({show: false})
  window.loadURL(`data:,window${id}`)
  windows.push(window)
}

app.once('ready', () => {
  for (let i = 1; i <= 5; i++) {
    createWindow(i)
  }

  setImmediate(function () {
    app.exit(123)
  })
})