gulp connect html extension resource name resolution

Question

I have a gulp-connect reload function

function reload(done) {
  server({
    livereload: true,
    root: '/home/kamil/my-website',
    port: 8080
  });
  done();
}

and I'm surprised to find that requesting localhost:8080/index doesn't resolve to the resource name index.html. Instead, I have to explicitly add the .html extension to the URL in order to get it, i.e. localhost:8080/index.html. Coming from JSP, where return "index"; works just as well as return "index.html"; that seems weird. Is there any reason for such a design decision? It's in the context of gulp connect, but maybe there is a general trend in js or frontend technologies? Generally speaking, is it often to be insensitive to HTML extension in resource resolution by such app servers?