JS callback async confusion

goodboy.js

get('dog', function(err, dog){
  if (err){ throw (err); }
  get('bone', function(err, bone){
    // The following variable in intentionally global.
    praise = dog + ' is a good boy, he deserves a ' + bone + '.';
    console.log('the praise is set.');
  });
});

// I would think the following line would throw an error because
// praise wouldn't be defined by the time it gets here.
// when the first async methd is executed(get 'bone'), isn't
// this the next line that is executed?
console.log( praise );


function get(item, callback){
  console.log('getting ', item);
  var items = {bone: 'milk bone', dog: 'Roger R. Woof-woof'};
  return callback(null, items[item]);
}

// Console output from running this file
// $ node goodboy.js
// getting  bone
// getting  dog
// the praise is set.
// Roger R. Woof-woof is a good boy, he deserves a milk bone.

goodboyfail.js

// Adding a delay on the get function porduces the expected Reference error

get('dog', function(err, dog){
  if (err){ throw (err); }
  get('bone', function(err, bone){
    praise = dog + ' is a good boy, he deserves a ' + bone + '.';
    console.log('the praise is set.');
  });
});

console.log( praise );


function get(item, callback){
  console.log('getting ', item);
  setTimeout(function(){
    var items = {bone: 'milk bone', dog: 'Roger R. Woof-woof'};
    return callback(null, items[item]);
  }, 0);
}

// Console output from running this file
// $ node goodboyfail.js
// getting  dog
//
// /Users/makenova/Desktop/b75a2672f497fa864a1f/goodboyfail.js:11
// console.log( praise );
//              ^
// ReferenceError: praise is not defined
//     at Object.<anonymous> (/Users/makenova/Desktop/b75a2672f497fa864a1f/goodboyfail.js:11:14)
//     at Module._compile (module.js:456:26)
//     at Object.Module._extensions..js (module.js:474:10)
//     at Module.load (module.js:356:32)
//     at Function.Module._load (module.js:312:12)
//     at Function.Module.runMain (module.js:497:10)
//     at startup (node.js:119:16)
//     at node.js:902:3

Question.md

What makes a JS function async?

Is it possible to write a custom asynchronous function without the use of JS's timer functions such as setTimeout and setInterval ?

I have two code examples below, one that succeeds(goodboy.js) and one that fails(goodboyfail.js). I originally thought, goodboy.js would fail because I assumed

1. Simply defining get with a callback function would make it asyncronous
2. praise would be undefined when it was executed.

However, the console.log messages seem to indicate that the get function executes syncronously. I got the expected behviour in goodboyfail.js by adding a delay.

Notes

1. I've ignored error handling
2. I am aware that the 0ms applied to the setTimeout(goodboyfail.js) is not actually a 0 second delay but will be the browser minimum ~4ms.