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In the last video we installed a typed definition file for faker as a quick side.

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One of those benefits of type definition files is that we can now hover over faker right here and then

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if you're on Mac hold down the command key or if you're on Windows hold down control.

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You'll notice that faker turns into a clickable link of sorts.

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If we now click on that we'll be taken to the typedef definition file that we just installed.

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Notice how the name of this file is index dot D dot t s traditionally type definition files are named

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with extensions of D dot T.S..

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So anytime you are looking at some typescript code and you see a file with that extension that means

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you are looking at a type definition file inside this file.

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You're going to find nothing but typescript syntax.

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So the only goal of this file right here is to describe the different types of values functions objects

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classes that exist inside the faker library.

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So there will not actually be any functions that are implemented inside of here.

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Instead you instead you will only see a definition of the different types that are available if you

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look inside of here we can actually use this as a source of documentation.

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So for example remember at the official documentation we looked at just a moment ago we saw that address

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module.

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So this right here is telling typescript that this library has a address object and inside of it are

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different functions like zip code city city prefix and so on.

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We can see the different arguments that each of them take and a different type of values that they return.

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So like I said we can use this file as kind of an alternate forms of documentation to understand how

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to work with a given library so in this case we can take a look at address.

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If we scroll down you'll notice the latitude and longitude are two functions inside there.

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We're gonna use those functions to actually randomly generate our latitude longitude as a quick side

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note I want you to notice how latitude longitude return Strings which is actually kind of not very typical

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usually we reflect latitude and longitude as numbers.

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So having them being returned here as a string means that might be a little bit unexpected and we might

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have to deal with that at some point in time but we'll just see what happens.

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All right I'm going to close this file and back inside of my user dot t s file.

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We're not going to do some initialization of our name.

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Latitude and longitude inside of our constructor.

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So inside the constructor as soon as we make an instance of a user we're going to randomly generate

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a name and assign it to that name property.

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So inside of here I'll say this dot name is going to come from faker.

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We're going to get the name module.

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Remember we saw that in the official documentation his name right here and we're going to generate a

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first name once again.

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We could find the existence of this function either by looking at the official documentation or just

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command clicking on faker and then search this thing for like first name and there it is.

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So here is the name module.

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There's the first name method.

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Even by looking at this documentation right here or this type definition file you'll notice that we

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even are told that we can taken a gender argument right here.

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This actually did not exist in the official documentation.

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So the type definition file actually gives us more information sometimes than a typedef or semi a documentation

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document actually does all right.

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So now we've generate the first name we can do the same thing for our latitude and longitude as well.

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Now here's a really quick note for you something that really gets people hung up when they are getting

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started with typescript at this point we have only tell told typescript that our class user is going

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to be of type or going to have a property called location and location will have an object with a latitude

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and longitude property here's the important thing.

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When we create an instance of a user location does not get automatically set to be an object.

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So in other words if we did right here a console log of this dot location we would see undefined or

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no.

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That means that if we tried to do direct assignment to latitude and longitude like this dot location

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dot lat equals you know some number we would actually see an error message and would say something like

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cannot read property of left of undefined so all we have done up here is said hey typescript we're going

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to have a location property it will be an object that has these two properties but we have not done

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any initialization for that yet.

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There is no object here when we create our user.

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So we are responsible for initialization of this object and the properties inside of it.

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So in other words that means to initialize latitude and longitude.

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We have to say this dot location is going to be an object with properties lat and LNG so we can try

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to initialize both Latin LNG will do you faker dot address dot latitude I'll get a comma at the end

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of that line and then faker dot address dot longitude like so even then I still see an error message

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if we mouse over this you'll notice that it says expected are right here type string is not assigned

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a ball to type no it's remember when we were looking at the documentation for latitude and longitude

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or the type definition filed just a second ago we saw that latitude longitude where functions that return

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Strings but we clearly said that latitude and longitude were gonna be numbers once again in my opinion

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this is kind of an oversight by the faker people and they really should be returning numbers here however

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that's just how they built this library.

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So we need to take the strings that are returned by latitude longitude and convert them into numbers

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to do so we have to do an actual conversion process like this is a string right here.

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So we have to convert that into an actual number.

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So to do so we're going to take a very javascript style approach we're gonna use the pass float function

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just to make sure you are aware of the pass float function is built into javascript it takes a string

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and returns a number that has a decimal value attached to it so we can call a pass float on both and

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the error goes away because now we are signing a number to both latitude and longitude All right.

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That's pretty much it.

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Let's take a quick pause right here.

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When come back the next video we're gonna start to actually make use of our class.

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So I'll see you in just a minute.