ok.js

#
# MAIN.JS
#

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

let win

function createWindow() {
    win = new BrowserWindow( {width: 800, height: 600})
    win.loadFile('index.html')
    win.webContents.openDevTools()

    win.on('closed', () => {
        win = null
    })
}

app.on('ready', createWindow)

app.on('window-all-closed', () => {
    if (process.platform != 'Darwin') {
        app.quit()
    }
})

app.on('active', () => {
    if (win == null) {
        createWindow()
    }
})

#
# HTML
#
<button class="nav-link active" id="login_window" role="tab" data-toggle="tab">
              <i class="material-icons">account_circle</i>
              Login
          </button>
              
#
# actions.js
#
const login_window = document.getElementById('login_window')
login_window.addEventListener('click', function(event) {
    console.log('okkk1')
    win.loadFile('index2.html')
})