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<li class="toc-entry toc-h2"><a href="#prepare">Prepare</a></li>
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<li class="toc-entry toc-h2"><a href="#project">Project</a></li>
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<h1 class="bd-title" id="content">Classes</h1>
<span class="lead">
<p class="bd-lead"></p>
<p>
JavaScript IV introduces you to the powerful paradigm of
Object Oriented Programming (OOP) in JavaScript. We will
take a deep dive into these topics:
</p>
<ul>
<li>The JavaScript Prototype object</li>
<li>constructor functions</li>
<li>Pseudo-classical Inheritence</li>
<li>
the <code class="highlighter-rouge">class</code> keyword
</li>
</ul>
<p>
By the end of the day you should be familiar with objects
and how to use Constructors and Classes to build out
objects and achieve inheritance across these objects.
</p>
</span>
<strong
>At the end of this module, you should be able to:</strong
>
<ul>
<li>describe and demonstrate how class syntax works</li>
<li>
convert a pseudo classically instantiated program into
class syntax
</li>
</ul>
</div>
<div class="alert alert-warning" role="alert">
<h4>Pro Tip</h4>
<p>
Accept criticism gracefully and learn from it. Criticism is
valuable for growth and development. When you ask for a
opinion in a professional setting, the chances of the person
is trying to hurt your feeling, or make you feel small or be
actively cruel is so vanishingly small that, despite
occasions where others are factually wrong with their
criticism, you should hold onto it like a precious gift.
</p>
</div>
<h2 class="display-4">
<a
id="prepare"
class="anchor"
href="#prepare"
aria-hidden="true"
><span class="octicon octicon-link"></span></a
>Prepare
</h2>
<p class="lead">Review each preclass resource before class.</p>
<div class="preclass">
<ul class="list-group list-group-flush">
<li class="list-group-item">
<div class="embed-responsive embed-responsive-16by9">
<iframe
class="embed-responsive-item"
src="https://www.youtube.com/embed/D3Yx_ohAet4"
frameborder="0"
allowfullscreen
></iframe>
</div>
</li>
<li class="list-group-item">
<div class="embed-responsive embed-responsive-16by9">
<iframe
class="embed-responsive-item"
src="https://www.youtube.com/embed/gnDkLbeof60"
frameborder="0"
allowfullscreen
></iframe>
</div>
</li>
</ul>
</div>
<h2 class="display-4">
<a id="learn" class="anchor" href="#learn" aria-hidden="true"
><span class="octicon octicon-link"></span></a
>Learn
</h2>
<h4 class="mark mb-3 p-2">
Learn to describe and demonstrate how class syntax works
</h4>
<p>
Because the original prototype system in JavaScript is rather
clunky, and because there are multiple ways to skin a cat
(achieve inheritance), we now have the
<code class="highlighter-rouge">class</code> keyword to
simplify our lives significantly. With the introduction of the
<code class="highlighter-rouge">class</code> keyword however,
we gain a lot of abstraction, which is why it is extremely
important for you have seen how to achieve inheritance with
what is known as the
<code class="highlighter-rouge">psuedo-classical</code>
inheritance pattern.
</p>
<p>
Once you are familiar with how the prototype works, how
inheritance is achieved through the
<code class="highlighter-rouge">psuedo-classical</code>
pattern and how to implement constructor functions, you’re
going to LOVE how easy it is to do this with the class
keyword.
</p>
<h5>Overview</h5>
<h3 id="classes">Classes</h3>
<p>
With ES6 we gained the ability to use what is known as the
<code class="highlighter-rouge">class</code> keyword. The
<code class="highlighter-rouge">class</code> keyword is what
we call “syntactic sugar” on top of the object built into
JavaScript and the object’s
<code class="highlighter-rouge">prototype</code> system. The
<code class="highlighter-rouge">class</code> keyword is
<strong>not</strong> a new way of achieving object-oriented
inheritance in JavaScript.
</p>
<p>
You already know how to work with classes because you know all
about
<code class="highlighter-rouge">constructor functions</code>
and the
<code class="highlighter-rouge">Object prototype</code>.
Working with constructor functions to achieve object creation
in JavaScript is fundamental to understanding how classes
work. Remember that
<strong
>classes in JavaScript are just special functions</strong
>.
</p>
<p>
There are two types of ways we can work with and define
classes (much like functions how there are multiple ways of
declaring/defining functions)
<code class="highlighter-rouge">class expressions</code> &
<code class="highlighter-rouge">class declarations</code>. The
pattern we learn today will be called
<code class="highlighter-rouge">class declarations</code>.
</p>
<p>Let us begin by observing some syntax:</p>
<div class="language-js highlighter-rouge">
<div class="highlight">
<pre
class="highlight"
><code><span class="kd">class</span> <span class="nx">Rectangle</span> <span class="p">{</span>
<span class="kd">constructor</span><span class="p">(</span><span class="nx">height</span><span class="p">,</span> <span class="nx">width</span><span class="p">)</span> <span class="p">{</span>
<span class="k">this</span><span class="p">.</span><span class="nx">height</span> <span class="o">=</span> <span class="nx">height</span><span class="p">;</span>
<span class="k">this</span><span class="p">.</span><span class="nx">width</span> <span class="o">=</span> <span class="nx">width</span><span class="p">;</span>
<span class="p">}</span>
<span class="p">}</span> <span class="o">*</span>
</code></pre>
</div>
</div>
<p>
Here we have declared a Rectangle class. It looks pretty
similar to the constructor functions that we’re used to;
however, this time, we’re deliberate about placing it inside
of the class. You can think of the constructor function as the
foundation of every class. When present, you’ll be building
your object’s properties (these get returned when you call
<code class="highlighter-rouge">new</code>) inside the
constructor’s body on the
<code class="highlighter-rouge">this</code> keyword.
</p>
<p>
Any properties you bound to your created object can be passed
in through the constructor method. In this case, we have
<code class="highlighter-rouge">height</code> &
<code class="highlighter-rouge">width</code> as attributes
that we’d like to store on our created object. Remember:
<strong>classes will return us objects</strong>.
</p>
<p>
Now, if I wanted to use this class to create an object, it
would look very much the same as constructor functions. All I
have to do is declare some variable and assign it to the class
by using the new keyword.
</p>
<p>
Let us declare a
<code class="highlighter-rouge">new</code> Rectangle and log
the result.
</p>
<div class="language-js highlighter-rouge">
<div class="highlight">
<pre
class="highlight"
><code><span class="kd">const</span> <span class="nx">newRect</span> <span class="o">=</span> <span class="k">new</span> <span class="nx">Rectangle</span><span class="p">(</span><span class="mi">400</span><span class="p">,</span> <span class="mi">800</span><span class="p">);</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">newRect</span><span class="p">);</span>
<span class="nx">Logs</span> <span class="nx">out</span><span class="p">:</span>
<span class="err"></span><span class="nx">Rectangle</span> <span class="p">{</span> <span class="nl">height</span><span class="p">:</span> <span class="mi">400</span><span class="p">,</span> <span class="nx">width</span><span class="p">:</span> <span class="mi">800</span> <span class="p">}</span><span class="err"></span>
</code></pre>
</div>
</div>
<h3 id="inheritance-w-classes">Inheritance w/ Classes</h3>
<p>
Inheritance is where classes shine. The
<code class="highlighter-rouge">extends</code> keyword, and
<code class="highlighter-rouge">super();</code> function make
it trivial to bind our classes together to achieve some simple
object inheritance. The
<code class="highlighter-rouge">extends</code> keyword will
abstract away any of the
<code class="highlighter-rouge">Class.call</code> syntax that
we’re used to.
<code class="highlighter-rouge">super()</code> tells a
parent’s constructor to be concerned with the child’s
attributes and abstracts away the
<code class="highlighter-rouge"
>Object.create(this, Class)</code
>
syntax that is trickier to understand.
</p>
<p>Here’s how Object inheritance works with classes:</p>
<div class="language-js highlighter-rouge">
<div class="highlight">
<pre
class="highlight"
><code><span class="kd">class</span> <span class="nx">Animal</span> <span class="p">{</span>
<span class="kd">constructor</span><span class="p">(</span><span class="nx">name</span><span class="p">)</span> <span class="p">{</span>
<span class="k">this</span><span class="p">.</span><span class="nx">name</span> <span class="o">=</span> <span class="nx">name</span><span class="p">;</span>
<span class="p">}</span>
<span class="nx">speak</span><span class="p">()</span> <span class="p">{</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="k">this</span><span class="p">.</span><span class="nx">name</span> <span class="o">+</span> <span class="dl">'</span><span class="s1"> makes a noise.</span><span class="dl">'</span><span class="p">);</span>
<span class="p">}</span>
<span class="p">}</span>
</code></pre>
</div>
</div>
<p>
Notice that <code class="highlighter-rouge">speak()</code> is
a method with some special syntax in this class. This method
will not be a method on the object, but it will live on the
object’s prototype instead, which is nifty when you’re worried
about memory and such.
</p>
<p>
If I wanted to create a sub-class from our Animal class, it’s
effortless.
</p>
<div class="language-js highlighter-rouge">
<div class="highlight">
<pre
class="highlight"
><code><span class="kd">class</span> <span class="nx">Dog</span> <span class="kd">extends</span> <span class="nx">Animal</span> <span class="p">{</span>
<span class="kd">constructor</span><span class="p">(</span><span class="nx">name</span><span class="p">)</span> <span class="p">{</span>
<span class="k">super</span><span class="p">(</span><span class="nx">name</span><span class="p">);</span>
<span class="p">}</span>
<span class="nx">speak</span><span class="p">()</span> <span class="p">{</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="k">this</span><span class="p">.</span><span class="nx">name</span> <span class="o">+</span> <span class="dl">'</span><span class="s1"> barks.</span><span class="dl">'</span><span class="p">);</span>
<span class="p">}</span>
<span class="p">}</span>
</code></pre>
</div>
</div>
<p>
Isn’t that so much nicer? No more
<code class="highlighter-rouge"
>.bind(), .call(), .apply()</code
>
and
<code class="highlighter-rouge">Object.create()</code> etc. We
simply just understand the little nuances and it works.
</p>
<p>And using this child class:</p>
<div class="language-js highlighter-rouge">
<div class="highlight">
<pre
class="highlight"
><code><span class="kd">const</span> <span class="nx">doggy</span> <span class="o">=</span> <span class="k">new</span> <span class="nx">Dog</span><span class="p">(</span><span class="dl">'</span><span class="s1">Grizzly</span><span class="dl">'</span><span class="p">);</span>
<span class="nx">doggy</span><span class="p">.</span><span class="nx">speak</span><span class="p">();</span>
<span class="o">---></span> <span class="dl">'</span><span class="s1">Grizzly barks.</span><span class="dl">'</span>
</code></pre>
</div>
</div>
<p>
This is an example derived directly from the MDN
documentation. So once you’re done learning from here, you can
head over there and check this out.
</p>
<h5>Follow Along</h5>
<p>
Now follow along with me as we build out some quick classes.
</p>
<div class="language-js highlighter-rouge">
<div class="highlight">
<pre
class="highlight"
><code><span class="kd">class</span> <span class="nx">Animal</span> <span class="p">{</span>
<span class="kd">constructor</span><span class="p">(</span><span class="nx">name</span><span class="p">)</span> <span class="p">{</span>
<span class="k">this</span><span class="p">.</span><span class="nx">name</span> <span class="o">=</span> <span class="nx">name</span><span class="p">;</span>
<span class="p">}</span>
<span class="nx">speak</span><span class="p">()</span> <span class="p">{</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="s2">`</span><span class="p">${</span><span class="k">this</span><span class="p">.</span><span class="nx">name</span><span class="p">}</span><span class="s2"> says, Hello!`</span><span class="p">);</span>
<span class="p">}</span>
<span class="p">}</span>
</code></pre>
</div>
</div>
<p>
Animal is going to be our
<code class="highlighter-rouge">base</code> class. All other
classes will inherit from Animal. So lets define a couple of
different animals:
</p>
<div class="language-js highlighter-rouge">
<div class="highlight">
<pre
class="highlight"
><code><span class="kd">class</span> <span class="nx">Dog</span> <span class="kd">extends</span> <span class="nx">Animal</span> <span class="p">{</span>
<span class="kd">constructor</span><span class="p">(</span><span class="nx">name</span><span class="p">)</span> <span class="p">{</span>
<span class="k">super</span><span class="p">(</span><span class="nx">name</span><span class="p">);</span>
<span class="p">}</span>
<span class="nx">speak</span><span class="p">()</span> <span class="p">{</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="s2">`</span><span class="p">${</span><span class="k">this</span><span class="p">.</span><span class="nx">name</span><span class="p">}</span><span class="s2"> barks!`</span><span class="p">);</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="kd">class</span> <span class="nx">Cat</span> <span class="kd">extends</span> <span class="nx">Animal</span> <span class="p">{</span>
<span class="kd">constructor</span><span class="p">(</span><span class="nx">name</span><span class="p">)</span> <span class="p">{</span>
<span class="k">super</span><span class="p">(</span><span class="nx">name</span><span class="p">);</span>
<span class="p">}</span>
<span class="nx">speak</span><span class="p">()</span> <span class="p">{</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="s2">`</span><span class="p">${</span><span class="k">this</span><span class="p">.</span><span class="nx">name</span><span class="p">}</span><span class="s2"> Meows!`</span><span class="p">);</span>
<span class="p">}</span>
<span class="p">}</span>
</code></pre>
</div>
</div>
<p>And if we want to use them:</p>
<div class="language-js highlighter-rouge">
<div class="highlight">
<pre
class="highlight"
><code><span class="kd">const</span> <span class="nx">bowWow</span> <span class="o">=</span> <span class="k">new</span> <span class="nx">Dog</span><span class="p">(</span><span class="dl">'</span><span class="s1">Grizzly</span><span class="dl">'</span><span class="p">);</span>
<span class="kd">const</span> <span class="nx">kitty</span> <span class="o">=</span> <span class="k">new</span> <span class="nx">Cat</span><span class="p">(</span><span class="dl">'</span><span class="s1">Fluffertons</span><span class="dl">'</span><span class="p">);</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">bowWow</span><span class="p">);</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="nx">kitty</span><span class="p">);</span>
<span class="nx">bowWow</span><span class="p">.</span><span class="nx">speak</span><span class="p">();</span>
<span class="nx">kitty</span><span class="p">.</span><span class="nx">speak</span><span class="p">();</span>
</code></pre>
</div>
</div>
<p>
Check it out! If you didn’t find this astounding, you will
once we convert the
<code class="highlighter-rouge">constructor functions</code>
we’ve built over to use the class keyword!
</p>
<h5>Challenge</h5>
<p>
For this challenge, we want you to build out a few classes
based on your ancestral tree. (If you’re not sure about any of
your family’s information go ahead and make up names like
“Grandpa” and “Grandma”).
</p>
<p>
Go back a few generations and create a
<code class="highlighter-rouge">Grandpa or Grandma</code>
class. Name either one for your parent’s parents.
</p>
<p>
Create a <code class="highlighter-rouge">Parent</code> class
named for one of your parents.
<code class="highlighter-rouge"
>Parent inherits from Grandpa/Grandma</code
>.
</p>
<p>
Create a <code class="highlighter-rouge">Child</code> class
(you) who inherits from
<code class="highlighter-rouge">Parent</code>.
</p>
<p>
Be sure to log out any methods that you use for this project.
Any features (i.e. eye color, hair color) that you’d inherit
from your ancestors, be sure to include as attributes and pass
them down the class chain. Every class should at least be
instantiated with the following attributes.
<code class="highlighter-rouge"
>name, birthPlace, eyeColor, hairColor</code
>.
</p>
<hr />
<h4 class="mark mb-3 p-2">
Learn to convert a pseudo classically instantiated program
into class syntax
</h4>
<p>
Now that you have had some experience writing constructor
functions to create new objects that inherit from each other,
it’s time to convert those pseudo classically instantiated
programs into class syntax.
</p>
<h5>Overview</h5>
<p>
Now that we have had plenty of practice with pseudo-classical
inheritance. We’ll take the time to convert our beautiful
little
<code class="highlighter-rouge">Person</code> constructor.
</p>
<p>Some critical notes on classes:</p>
<ul>
<li>
The <code class="highlighter-rouge">object</code> our class
returns will have attributes assigned to it from the
<code class="highlighter-rouge">constructor()</code>
function.
</li>
<li>
All methods attached to the class body will be stored on the
<code class="highlighter-rouge">Objects</code> prototype in
a special way. There is a bit more magic here than just
<code class="highlighter-rouge"
>Object.create(Foo.prototype);</code
>
and
<code class="highlighter-rouge"
>Class.call(this, attrs);</code
>
But now that we know this, we can accept that the class
keyword does this gloriously for us.
</li>
<li>
The ‘extends’ keyword is used to
<code class="highlighter-rouge">extend</code> a parent
object. A clue to finding out if a class is a
<code class="highlighter-rouge">sub-class</code> is to look
for extends.
</li>
<li>
Finally, if you’re going to use
<code class="highlighter-rouge">extend</code>,
<code class="highlighter-rouge">super()</code> needs to be
called from within the constructor function. This is to pass
any new attributes back up to the constructor of the parent
object.
</li>
</ul>
<p>
Examples found below as we refactor our code from the previous
objective:
</p>
<div class="language-js highlighter-rouge">
<div class="highlight">
<pre
class="highlight"
><code><span class="kd">function</span> <span class="nx">Person</span><span class="p">(</span><span class="nx">attributes</span><span class="p">)</span> <span class="p">{</span>
<span class="k">this</span><span class="p">.</span><span class="nx">age</span> <span class="o">=</span> <span class="nx">attributes</span><span class="p">.</span><span class="nx">age</span><span class="p">;</span>
<span class="k">this</span><span class="p">.</span><span class="nx">name</span> <span class="o">=</span> <span class="nx">attributes</span><span class="p">.</span><span class="nx">name</span><span class="p">;</span>
<span class="k">this</span><span class="p">.</span><span class="nx">homeTown</span> <span class="o">=</span> <span class="nx">attributes</span><span class="p">.</span><span class="nx">homeTown</span><span class="p">;</span>
<span class="p">}</span>
<span class="nx">Person</span><span class="p">.</span><span class="nx">prototype</span><span class="p">.</span><span class="nx">speak</span> <span class="o">=</span> <span class="kd">function</span> <span class="p">()</span> <span class="p">{</span>
<span class="k">return</span> <span class="s2">`Hello, my name is </span><span class="p">${</span><span class="k">this</span><span class="p">.</span><span class="nx">name</span><span class="p">}</span><span class="s2">`</span><span class="p">;</span>
<span class="p">};</span>
</code></pre>
</div>
</div>
<div class="language-js highlighter-rouge">
<div class="highlight">
<pre
class="highlight"
><code><span class="kd">class</span> <span class="nx">Person</span> <span class="p">{</span>
<span class="kd">constructor</span><span class="p">(</span><span class="nx">attributes</span><span class="p">)</span> <span class="p">{</span>
<span class="k">this</span><span class="p">.</span><span class="nx">age</span> <span class="o">=</span> <span class="nx">attributes</span><span class="p">.</span><span class="nx">age</span><span class="p">;</span>
<span class="k">this</span><span class="p">.</span><span class="nx">name</span> <span class="o">=</span> <span class="nx">attributes</span><span class="p">.</span><span class="nx">name</span><span class="p">;</span>
<span class="k">this</span><span class="p">.</span><span class="nx">homeTown</span> <span class="o">=</span> <span class="nx">attributes</span><span class="p">.</span><span class="nx">homeTown</span><span class="p">;</span>
<span class="p">}</span>
<span class="nx">speak</span><span class="p">()</span> <span class="p">{</span>
<span class="k">return</span> <span class="s2">`Hello, my name is </span><span class="p">${</span><span class="k">this</span><span class="p">.</span><span class="nx">name</span><span class="p">}</span><span class="s2">`</span><span class="p">;</span>
<span class="p">}</span>
<span class="p">}</span>
</code></pre>
</div>
</div>
<p>Let’s review:</p>
<ul>
<li>
<code class="highlighter-rouge">speak</code> is now assigned
to the object’s prototype. (open the console and show this
off after you instantiate an object.)
</li>
<li>
<code class="highlighter-rouge">this</code> is a single
class, meaning it is not
<code class="highlighter-rouge">extending</code> a parent
class. We’ll get to
<code class="highlighter-rouge">extend</code>s soon.
</li>
<li>
The code is clean now! Instead of having to reference the
object’s prototype over and over to create methods on it,
you can just add them to the class body. This is how we use
classes today. You’ll get plenty of time to use this when we
get to React. React uses classes all the time.
</li>
</ul>
<p>
Classes come in handy when we have children objects that will
be sub-classes of their parents. We accomplished this in the
previous module with
<code class="highlighter-rouge">Child</code> (see below).
</p>
<div class="language-js highlighter-rouge">
<div class="highlight">
<pre
class="highlight"
><code><span class="kd">function</span> <span class="nx">Child</span><span class="p">(</span><span class="nx">childAttrs</span><span class="p">)</span> <span class="p">{</span>
<span class="nx">Person</span><span class="p">.</span><span class="nx">call</span><span class="p">(</span><span class="k">this</span><span class="p">,</span> <span class="nx">childAttrs</span><span class="p">);</span> <span class="c1">// this is the special sauce</span>
<span class="k">this</span><span class="p">.</span><span class="nx">isChild</span> <span class="o">=</span> <span class="nx">childAttrs</span><span class="p">.</span><span class="nx">isChild</span><span class="p">;</span> <span class="c1">// this will be a special attribute to Child</span>
<span class="p">}</span>
<span class="nx">Child</span><span class="p">.</span><span class="nx">prototype</span><span class="p">.</span><span class="nx">checkIfChild</span> <span class="o">=</span> <span class="kd">function</span><span class="p">()</span> <span class="p">{</span>
<span class="k">if</span><span class="p">(</span><span class="k">this</span><span class="p">.</span><span class="nx">isChild</span><span class="p">)</span> <span class="p">{</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="s2">`</span><span class="p">${</span><span class="k">this</span><span class="p">.</span><span class="nx">speak</span><span class="p">}</span><span class="s2"> and I am a child object`</span><span class="p">);</span>
<span class="p">}</span>
<span class="p">};</span>
</code></pre>
</div>
</div>
<p>With classes, we can rewrite that function like this:</p>
<div class="language-js highlighter-rouge">
<div class="highlight">
<pre
class="highlight"
><code><span class="kd">class</span> <span class="nx">Child</span> <span class="kd">extends</span> <span class="nx">Parent</span> <span class="p">{</span>
<span class="kd">constructor</span><span class="p">(</span><span class="nx">childAttrs</span><span class="p">)</span> <span class="p">{</span>
<span class="k">super</span><span class="p">(</span><span class="nx">childAttrs</span><span class="p">);</span>
<span class="k">this</span><span class="p">.</span><span class="nx">isChild</span> <span class="o">=</span> <span class="nx">childAttrs</span><span class="p">.</span><span class="nx">isChild</span><span class="p">;</span>
<span class="p">}</span>
<span class="nx">checkIfChild</span><span class="p">()</span> <span class="p">{</span>
<span class="k">if</span><span class="p">(</span><span class="k">this</span><span class="p">.</span><span class="nx">isChild</span><span class="p">)</span> <span class="p">{</span>
<span class="nx">console</span><span class="p">.</span><span class="nx">log</span><span class="p">(</span><span class="s2">`</span><span class="p">${</span><span class="k">this</span><span class="p">.</span><span class="nx">speak</span><span class="p">}</span><span class="s2"> and I am a child object`</span><span class="p">);</span>
<span class="p">}</span>
<span class="p">}</span>
</code></pre>
</div>
</div>
<p>
Now we’re going to make
<code class="highlighter-rouge">fred</code> and
<code class="highlighter-rouge">pebble</code> into objects and
see what they look like! Be ready to be blown away!
</p>
<div class="language-js highlighter-rouge">
<div class="highlight">
<pre
class="highlight"
><code><span class="kd">const</span> <span class="nx">fred</span> <span class="o">=</span> <span class="k">new</span> <span class="nx">Person</span><span class="p">({</span>
<span class="na">age</span><span class="p">:</span> <span class="mi">35</span><span class="p">,</span>
<span class="na">name</span><span class="p">:</span> <span class="dl">'</span><span class="s1">Fred</span><span class="dl">'</span><span class="p">,</span>
<span class="na">homeTown</span><span class="p">:</span> <span class="dl">'</span><span class="s1">Bedrock</span><span class="dl">'</span>