Async Console

Async Console

https://github.com/getify/You-Dont-Know-JS/blob/master/async%20&%20performance/ch1.md#async-console

there are some browsers and some conditions that console.log(..) 
does not actually immediately output what it's given.

The main reason this may happen is because I/O is a very slow and blocking 
part of many programs (not just JS).

So, it may be more performant (from the page/UI perspective) for a browser to 
handle console I/O asynchronously in the background.

var a = {
    index: 1
};

// later
console.log( a ); // ??

// even later
a.index++;

it's possible this same code could run in a situation where the browser felt 
it needed to defer the console I/O to the background, in which case it's possible
that by the time the object is represented in the browser console, the a.index++ 
has already happened, and it shows { index: 2 }.

https://github.com/getify/You-Dont-Know-JS/blob/master/async%20&%20performance/ch1.md#async-console

"Note: If you run into this rare scenario, the best option is to use breakpoints in your JS debugger instead of relying on console output. The next best option would be to force a "snapshot" of the object in question by serializing it to a string, like with JSON.stringify(..)."