The concept of the web as an application platform has never been more popular, but the tools used to create these so-called “web apps” are still fraught with pitfalls that are often ignored or misunderstood. Single-page web app frameworks have gained traction because they can easily be used to create fast, complex applications that feel much more solid and interactive than traditional websites. But this benefit, and the changes in mindset and development practices that accompany it, comes at the cost of basic browser functionality that web developers sometimes take for granted.

With vendors making it increasingly difficult to disable, we can get lulled into thinking that we don’t need to provide a fallback for users whose browsers don’t execute JavaScript. But explicitly choosing to disable JavaScript is far from the only reason a user’s browser might not run it. Government Digital Service (GDS), the team that maintains the UK government website, found that, out of every 500 visitors to GOV.UK, five did not receive JavaScript, but only one had JavaScript explicitly disabled. The other four could be missing out on JavaScript for any of several reasons: an overzealous corporate proxy server; a request for JavaScript timing out due to high latency; or even an unnoticed syntax error.

https://alistapart.com/article/let-links-be-links/

Your website should work without JavaScript. Or at least the core functionalities.