feat: new javascript example v2

[MatheusLasserre]

New example more friendly to newbies.

@gnumoreno

[matthewelwell]

This looks good on the whole, I like how readable the code is in index.js. I've added a few minor comments.

[MatheusLasserre]

Hey, @matthewelwell! Do i need to modify or add anything else here?

[kyle-ssg]

I'd really love to standardise all of the JS examples with shared markup, CSS, content and demonstation. Perhaps what I'll do is use some of this PR as inspiration. Thanks very much for this

[MatheusLasserre]

I'd really love to standardise all of the JS examples with shared markup, CSS, content and demonstation. Perhaps what I'll do is use some of this PR as inspiration. Thanks very much for this

If this one was approved, I was thinking about gradually doing for the others JS Examples in my spare time. If you wanted, of course. But anyway, glad it helped!