Of course, such things are perfectly possible and for an image editor I'd consider in-browser js superior to anything but native apps.

However, consider this, you want an app that has to use a database, you can't store everything on the client or use things like Dropbox integration. Plenty of situations where you want that, but that just can't be done with clientside js without also making your database acces keys and encryption keys available to all. So all in all, it depends on what sort of app you want to build or form your course around

Or I just use node on the server side and write the server part also in js?

This was not about building anything sensible, but just to counter the point that js allows you less than php.

I think today the only big language with is a pain to setup is perl, java and sometimes python, the rest is just a matter of ecosystem, needs and personal taste.

Just because it can be done doesn't mean it's the ideal way to do it or to learn.

This was about your post saying you can't do anything with only JS and me disagreeing, not on how sensible language X or methode X is for anything.

Nobody would write a php app without js today and you can use js server side with nodejs, same as php and php fpm.

> your post saying you can't do anything with only JS

I ... didn't say that?

I meant your comment:

>Let's be fair: you're going to be very limited in terms of the type of web site you can make with this approach compared with a PHP app via web server

Which translates to me that you have the impression that JS is limited in usage, which it simply isn't.

Things like webrtc and other node, changed the way JS can be used and for the things it can be used.

That's not a fair translation of what I said at all.