Recently some JavaScript quizzes appear then and there with the competitive titles wondering whether “you know JavaScript”? The recent quizzes were by kangax, Dmitry Baranovskiy and by Nicholas C. Zakas. All that quizzes are interesting, many questions though are mostly theoretical rather than practical.
And again just for fun, I suggest another ECMAScript quiz. I won’t use some boring things such as “a+++b”; but I will more sophisticated 😉 Some interesting questions are collected from newsgroups, mailing lists, forums and from my own.