Javascript object shorthand

Asked Feb 26 '17 at 00:09

Active Feb 26 '17 at 00:22

Viewed 40 times

I'm reading the following question:

(function(){
  var a = b = 3;
})();

console.log("a defined? " + (typeof a !== 'undefined'));
console.log("b defined? " + (typeof b !== 'undefined'));

it says var a=b=3 is a shorthand for:

b=3;
var a=b;

So I solved another question

var foo = {n: 1};
var bar = foo;
foo.x = foo = {n: 2};

Question: What is foo.x?

So I'm assuming it's a shorthand for:

foo = { n:2 }
foo.x = foo

But, solution is other way around. It's undefined.

Can someone explain how is it undefined?

edited Feb 26 '17 at 00:22

guest271314

asked Feb 26 '17 at 00:09

TechnoCorner

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You're not being clear: _It's undefined_ What's undefined? `a`? Of course it is, a variable declaration being referenced outside of its scope can't be accessed. – Patrick Roberts Feb 26 '17 at 00:12
@PatrickRoberts `foo.x` is `undefined` – guest271314 Feb 26 '17 at 00:13
@PatrickRoberts can you explain what does `foo.x = foo = {n: 2};` mean? maybe that will make things clear for me. I'm assuming it's foo = {n:2} then foo.x = foo; – TechnoCorner Feb 26 '17 at 00:15
@scraaappy thank you :-) – TechnoCorner Feb 26 '17 at 00:15

Javascript object shorthand

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