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Welcome back in the end of the last video we saw that when we called our constructor function we did

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not return anything.

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The entire purpose of a constructor function is to construct objects.

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So when we call the function we'd really like to have a new object be created.

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Unfortunately that's not happening right now.

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But the good news is we can fix our problems by using the new keyword when we use the new keyword.

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Everything magically works.

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The first house variable is now an object with the bedrooms bathrooms and number of square feet property

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.

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But let's see just exactly what the new keyword does.

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Just like the key word this understanding with the new keyword does can be quite tricky.

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But review the slides.

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Remember these rules and most importantly try coding a couple of examples.

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It will really help your attention of the material.

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We see that the new keyword is being used with a function.

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In fact the new keyword must be used with a function or else we'll get a type error.

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Let's see why that's the case.

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Examining just what the new keyword does first.

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It creates an object out of thin air.

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Second it sets the value of the keyword this in the constructor function which is being used with.

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To be that the object that was just created.

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Third it adds an implicit return.

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This at the end of the function so that the object created using the new keyword can be returned from

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the function.

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Finally and this one is the most tricky.

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It adds a property on the empty object which can be accessed using double underscore Prato double underscore

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this double underscore is commonly called Dunder.

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So this property is also known as Dunder Prato the Dunder Prato property links the object that was just

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created to the prototype property on the constructor function.

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That last sentence may have seemed like a blur but don't worry too much for now we're going to cover

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this in painstaking detail.

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For now let's practice by making a constructor function for a dog.

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Each dog should have a name and an age as a bonus and a function for each dog object created from the

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function called Bark.

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This function should cancelled out log the name of the dog added to the string just barked pause the

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video and try to figure this out.

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So what did you come up with.

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Hopefully it looks something like this.

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Here we have a constructor function for a dog.

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This function takes in two parameters.

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Name and age.

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Remember that you can mean your parameters anything.

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But since we want to attach properties onto the object that will create called name and age we should

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probably name our parameters.

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The same thing inside of this function where setting properties on the keyword this equal to the value

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of what is passed to the function as well as adding a function called Barch on to the keyword this which

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canceled out logs the first name property concatenated with the string just parked on the next lines

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.

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We're creating two variables rusty and Feydeau and setting them equal to the value of the dog constructor

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function being invoked with the new keyword.

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Now before we recap with a new keyword does pause the video and see if you remember any of those four

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things.

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First it creates an empty object out of thin air.

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Second it then sets the value of the keyword.

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This in the function which is being used with to be the empty object that was just created.

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Third it adds an implicit return.

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This at the end of the function so that the object created using the new keyword can be returned from

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the function.

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Fourth it adds the Dunder Prato property onto the object that was just created.

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In this video we examine how to use the keyword new to create objects from constructor functions.

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We learned about the four things that the new keyword does which I highly encourage you to review because

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we'll be covering this in much more depth and knowing the fundamentals is essential in the next video

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.

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We're going to talk about using more than one constructor function and how we can refactor our code

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to make it even cleaner.

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See that