As far as does this implement enough JavaScript features for websites to run, https://test262.report/ https://test262.report/ looks really promising! You would

As far as does this implement enough JavaScript features for websites to run, https://test262.report/ https://test262.report/ looks really promising! You would have to hook it up to DOM and network and all sorts of other APIs normally provided by browsers, though. One reason you might not want to build a general-use browser on QuickJS is performance. QuickJS is one of the fastest JS interpreters in its weight class, but engines like V8 achieve much better runtime speed by using fifty times the code to do all kinds of complicated just-in-time optimizations. Websites built in frameworks like React are often bottlenecked by JS engine performance (spending 100ms or more just doing tons and tons of object instantiations and function calls and stuff), so a QuickJS browser probably wouldn't provide a good experience for those.