Is there a free website provided that allows JavaScript?

This is not an issue of what the hosting supports; websites and stylesheets are just text files.

Proper support of HTML5, external stylesheets and JavaScript have to be implemented in the browser looking at the web site. Since that's all standard, every current browser will support all of this.

In other words, even the most basic web hosting will support your requirements (since it's like asking for a car with wheels, every car has them).

Only when it comes to PHP or databases will you need a webhost that specifically supports them.

I used to recommend 000webhost.com, but I've read some mixed reviews. If this is just for experimenting (and not for a business or the like), try them.

Thank you. Yes, it's a useful test site. But I don't think it will allow a full website (maybe 15-20 pages) to be hosted there.

Is $2.5/month really that much for a decent paid hosting, where you can put up a site without ads and restrictions?