But if your web page is a complex application, having to support no-JS either shuts you out from from a huge set of interface tools, or forces you to maintain two interfaces in tandem. To me, 2% doesn't justify that, particularly when you can just politely inform the user that their browser has a significant feature disabled, and inform them how they can remedy the situation so that your site works.
I suppose it could be implemented as an Applet, but what's important is that Markup.io is exactly the sort of thing that Javascript exists for, really. And yes, disabling JS will break it, completely, and yes, I think that's perfectly forgivable.
On the whole, I agree that my blog should degrade, and data-entry type applications should work as well, but saying that everything should is completely overlooking an entire category of application for which it's perfectly acceptable, in my opinion.
By the way, not sure if you're the author of Markup.io, but it's pretty cool.
Consider GMail. How awesome would it be if you didn't have to wait for its "Loading..." progress bar? It takes 2-4 seconds for that to go away on my computer. If you design for progressive enhancement, you can interact immediately and when JS is ready, it simply enhances what's already there. If done right, it's all the same interface.
If you don't mind waiting, your users may not agree: Google and Amazon both have noted significant losses in revenue at page delays much shorter than 2 seconds.
Well, taking a look at "Basic HTML view"... considerably less awesome.
Instead of making two interfaces, they should make one interface. If JavaScript hasn't loaded yet (or if it's disabled), the majority of the interface can still be available immediately.
JavaScript should always add to the experience. It doesn't make sense to show GMail's Chat widget until JS is loaded-- but it really doesn't make sense to show nothing at all until the Chat JS downloads and runs!
You should be able to show the message list right away. You can start scanning your messages immediately. You can click normal links and submit forms.
Bonus for JS enabled users: a few seconds later the links, buttons, etc. all get hooked up to JavaScript. The Chat widget appears. By the time you click, things may even happen all AJAXy-- and it appeared to load instantly by loading JS in the background.
Now that's awesome.
