planetproto/exercises/090_implicit_this/problem.md

A Workshop for understanding JavaScript prototypes

'this' is assigned implicitly
-------------------

When we use `new` with a function, JavaScript injects an implicit reference to the new object being created in the form of the `this` keyword. It also returns this reference implicitly at the end of the function.

When we do this:

```js
function Alien() {
	this.kind = 'alien';
}

var zippy = new Alien();
zippy.kind; //=> 'alien'
```

Behind the scenes it is like doing something like:

```js
function Alien() {
	var this = {}; // not valid JavaScript, just for illustration
	this.__proto__ = Alien.prototype;
	
	this.kind = 'alien';
	
	return this;
}
```

But keep in mind that the implicit `this` is only assigned to a new object when using `new`. If you forget the `new` keyword then `this` will be the global object. Of course forgetting `new` is a cause of multiple bugs, so don't forget `new`.

One popular convention is to capitalize the first letter of a function when it is intended to be used as a function constructor e.g. `Alien`, so you know straight away that you are missing the `new` keyword.

Challenge
---------

Follow the instructions in the boilerplate file created.
A file 090.js with the necessary boilerplate has been created for you.