Asynchronous JavaScript (book)

Answer three questions on javascript. If any of them makes it difficult for you, you should read Trevor Burnham's excellent book, Async JavaScript . A total of 90 pages, but topics such as the JavaScript event loop, synchronicity / asynchrony, single-threading / multithreading (workers), promises, fibers and much more interesting are discussed here.

So what does the following code give out?

for (var i = 1; i <= 3; i++) { setTimeout(function(){ console.log(i); }, 0); }; 

UPD The second question is removed - a different implementation in browsers.

How many (approximately) times does setInterval(func, 0) in a second in a browser?

 var fireCount = 0; var start = new Date; var timer = setInterval(function() { if (new Date - start > 1000) { clearInterval(timer); console.log(fireCount); return; } fireCount++; }, 0); 

If you are wondering why this is the case, the answers are in the book .
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