builder.js

const fs = require('fs')
const path   = require('path')
const performance = require('perf_hooks').performance
const gi = require('..')
const Gdk = gi.require('Gdk', '3.0')
const Gtk = gi.require('Gtk', '3.0')

gi.startLoop()
Gtk.init()

const gladeFile = path.join(__dirname, './builderExample.glade')
const builder = Gtk.Builder.newFromFile(gladeFile)
const win = builder.getObject('mainWindow')

win.setDefaultSize(600, 400)
win.on('show', Gtk.main)
win.on('destroy', Gtk.mainQuit)

const closeButton = builder.getObject('closeButton')
closeButton.on('clicked', () => { win.close(); console.log('window closed') })

const actionButton = builder.getObject('actionButton')
actionButton.on('clicked', () => {

  let start = performance.now()

  Promise.resolve().then(() => {
    console.log('event promise.then() called, ' + (performance.now() - start))
  })

  process.nextTick(() => {
    console.log('event nextTick() called, ' + (performance.now() - start))
  })
})

const label = builder.getObject('helloLabel')
label.setText('Hello World!')

let action = function() {
  return new Promise((resolve) => {
    resolve('CHANGED')
    console.log('new Promise(...)  called')
  })
}

let start = performance.now()
action().then(res => {
  console.log('promise.then() called, ' + (performance.now() - start))
  label.setText(res)
})

process.nextTick(() => {
  console.log('nextTick() called')
  Promise.resolve().then(() => console.log('inner promise.then() called'))
})

win.showAll()