During the end of the day as well as a good evening, I wanted to get back in practice with PWA and the cache manager for offline mode in order to serve a web page even without an internet connection.

I looked into it, and after reading Progessive Web Apps from Google and tweaking some scripts to make it work, I managed to integrate it.

So I shared all this with you on Github:

• Progressive Web Apps
• Service Workers
• Offline Mode
• Randomize letters
• Install on your device (Computer on Chrome, all smartphones with Firefox or Chrome)

Starting in Chrome 73, Progressive Web Apps are now supported on all desktop platforms, including Chrome OS, Linux, Mac, and Windows. Link to post

This name of the project named Randomize_letter.
Also created number version here.

function Load() {
    let l = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    const out = l.charAt(Math.floor(Math.random() * l.length)) // Randomize !
    document.getElementById('random').textContent = out // Get ID 'random' for edit the text context
    document.title = out // Edit the title of page
}

I really like PWA and its features, because you can now create a native application on smartphones without having to update the Android/IOS and Web side code.