HELP Problem communicating main -> renderer

[Irraky]

Hello,
I'm new in the world of Java Script.
I use Electron-vue and I have some problems with this module.

I am able to send message from renderer to main and get a beautiful unicorn.
But when I have to do the reverse, I'm stuck.
I tried to put the main part in my main.js.
Then,

const win = electron.BrowserWindow.getFocusedWindow();

returns 'undefined'.

I also tried to put it in main/index.js at the end of my file (it's the file that create the window of the app).
And then it returns 'null'.

I have really no idea to make all things in order... Can someone help me please?

(if you understood nothing to what is the files I am talking about, here is my project: https://github.com/Irraky/test_mDNS)

[Irraky]

Finally succeed!!!
Got help from someone and end with that:

main/index.js

const ipc = require('electron-better-ipc')

setInterval(() => {
  (async () => {
    const emoji = await ipc.callRenderer(mainWindow, 'get-emoji', 'unicorn')
    console.log('Received from renderer', emoji)
  })()
}, 2000)

Main.vue

<script>
  const ipc = require('electron-better-ipc')

  function getEmoji (emoji) {
    if (emoji === 'unicorn') {
      return '🦄'
    }
    return emoji
  }

  export default {
    name: 'jsonformat',
    created () {
      ipc.answerMain('get-emoji', async emojiName => {
        const emoji = await getEmoji(emojiName)
        return emoji
      })
    }
  }
</script>

That works as expected :3