We do not need yet another JavaScript learning resource, we have good ones. Mozilla Developer Network is the best one, but there's also Free Code Camp, Eloquent JavaScript and javascript.info among many others. Don't write a resource for the sake of doing so unless you can bring something new to the table.
This is totally scummy. There's no way I can see to go to the upgrade page. Instead, it forces you to complete the lessons up to it before asking you to pay $25 for continued access. So it requires time investment first. Doesn't tell you the price first either.
Asking for $25 just to learn about arrays is purely abysmal. This "course" also doesn't even seem to go over exceptions, but I can't know that for sure because I'm not paying $25 to see the expanded table of contents. Also don't like that you're charging $25 before I can even learn about the DOM because half of this is incomplete.
I like that this teaches you not to use the var keyword! Pleasant to see that for once. That's the best thing I have to say about this.
Can't skip any lessons at all, even to browse.
Back button does not do what it should on some pages. Hitting "Next" should not refresh the page if I cannot go to the next page. I was somehow able to trigger a bug where I didn't complete two challenges and it marked them as completed.
Automatically sending me emails when I don't use your application for three days without asking me first, I have to figure out it's what a mail icon in the menu toggles. Awesome UX.
Nice that I can't send a message to support without letting Drift send me emails about upcoming promotions.
Edit: The purchase page tells me $25, but the payment prompt says 25 euro. Seems awfully like trying to mislead customers purposefully to pay more. Easy to miss.