Objects

The most powerful data structure in JavaScript is an object. These can be used to represent entities.

Let's look at why we might use objects.

Imagine you are storing data about yourself within your code:

Your name can be represented in JavaScript by a string.
Whether you like spicy food can be represented by a boolean.
Your age can be represented by a number.
Your favourite books can be represented by an array.

const michaelsName = "Michael";
const michaelsAge = 27;
const doesMichaelLikeSpicyFood = true;
const michaelsFavouriteBooks = ["The old man and the sea", "You dont know JS"];

But how do you group all of these facts about a person together? How do you represent a person?

The answer is to use objects - an object is a set of key-value pairs that is used to represent...anything!

const michael = {
  name: "Michael",
  age: 27,
  likesSpicyFood: true,
  favouriteBooks: ["The old man and the sea", "You dont know JS"],
};

That's instantly a much clearer representation of a person than the 4 seperate values we created above:

The michael object has 4 keys - name, age, likesSpicyFood, favouriteBooks.
The values of those keys are 'Michael', 27, true, and ['The old man and the sea', 'You dont know JS'] respectively.

You can add as many keys as you like, and they can have any values you like.

To access the value of a key, you can use dot notation:

michael.name; // 'Michael'
michael.age; // 27
michael.likesSpicyFood; // true
michael.favouriteBooks; // ['The old man and the sea', 'You dont know JS']

It's also possible to use square bracket notation

It's worth repeating that objects are the most powerful data structure available in JavaScript. They allow us to model the real world in a simple and flexible way, and are the foundation of Object Oriented Programming, which we will be focussing on in the next few weeks.

As the W3Schools article linked to at the bottom says:

In JavaScript, objects are king. If you understand objects, you understand JavaScript.

There are 10 object-related challenges for you to complete with your pair. Most of these build on the concepts from the provious challenges.

To run the tests for this challenge, run npm test -- objects

In the same manner as before, try to fix all of the failing tests.

Run the tests
Read the error message
Write some code to fix that message
Repeat

And again, commit to git regularly, and use the links provided and google to help you if you get stuck!

You can find the finished example repo here (dont use before you attempt whole exercise on your own ;))

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