Javascript function results

Question

I just started to learn javascript and programming overall. I found these examples and trying to figure out results of those two functions.

First:

(function(){
  var x = y = 11; 
})();  
console.log("x = " + (typeof x !== 'undefined')); 
console.log("y = " + (typeof y !== 'undefined'));

Results are true and false. Is it because var x is declared with var keyword so it is local var and y is not?

and second example:

(function(){
  console.log("a");
  setTimeout(function(){console.log("x")}, 1000);      
  setTimeout(function(){console.log("y")}, 0);      
  console.log("b"); 
})();

Please explain me the second example? If I got it right, setTimeout will wait for execution even if time is set to 0.

Thanks

You answered your first question yourself. What is to be explained in the second example? I don't see any strange result. Plus, why you ask two distinct, unrelated questions in a single post? — XCS, Oct 23 '16 at 22:53
What is algorithm here? what you dont understand in the second example,please be clear about it — Geeky, Oct 23 '16 at 22:54
In first I just wanted to be sure that I got it right. And in second why is executed in that order? why first, console logs then timeout functions? — wired, Oct 23 '16 at 22:54
For the first question, you're basically assigning the same value to different variables — Mueyiwa Moses Ikomi, Oct 23 '16 at 22:55
See [here](http://stackoverflow.com/questions/779379/why-is-settimeoutfn-0-sometimes-useful) for second example. — Andrew Li, Oct 23 '16 at 22:56

score 2 · Accepted Answer · answered Oct 23 '16 at 23:06

First: Correct. If you'd remove the 'var' from the 'x'-declaration that variable would also be available outside the function scope.

Second: The javascript function 'setTimeout' starts an asynchronous operation. In other words, the passed function gets added at the end of the queue to be operated at a later time, even if the passed time is 0ms. The 'console.log' functions run synchronously, so they always will be executed before the functions given with the 'setTimeout'-function.

Javascript function results

1 Answers1