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In the last video, we installed a type definition file for Fakher as a quick side, one of those benefits

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of type definition files is that we can now hover over Fakher right here.

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And then 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 Fakher turns into a clickable link of sorts.

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

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Notice how the name of this file is indexed Deetz.

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Traditionally type definition files are named with extensions of deetz.

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So any time 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.

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Inside this file, you're going to find nothing but typescript syntax, so the only goal of this file

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right here is to describe the different types of values, functions, objects, classes that exist inside

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the FAKHER Library.

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

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

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If you 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

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address 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 the different type of values that they

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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.

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So in this case, we can take a look at address, if we scroll down, you'll notice the latitude and

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longitude are two functions inside there and we're going to use those functions to actually randomly

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generate our latitude and longitude.

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As a quick side note, I want you to notice how latitude, longitude, return strings, which is actually

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kind of not very typical.

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Usually we reflect the 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.

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

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All right.

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So I'm going to close this file.

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And back inside of my user daughter's file, 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 your I'll say this DOT name is going to come from FACHER.

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We're going to get the name module.

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Remember, we saw that in the official documentation here, his name right here.

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And we're going to generate a first name.

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Once again, we could find the existence of this function either by looking at the official documentation

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or just command clicking on Fakher and then search this thing for like first name.

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And there it is, so here's the name module, there's the first name method, even by looking at this

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documentation right here or this type definition file.

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You'll notice that we even are told that we can take in 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 he typed or submitted

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documentation document actually does.

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All right, so now we've generally the first name, we can do the same thing for our latitude and longitude

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as well.

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Now, here's a really quick note for you.

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Something that really gets people hung up when they are getting started with typescript.

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At this point, we have only till told TypeScript that our class user is going to be of type or going

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to have a property called location and location will have an object with a latitude and longitude property.

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Here's the important thing, when we create an instance of a user location does not get automatically

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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

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or null.

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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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that equals some number, we would actually see an error message and would say something like cannot

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read property of Latt of undefined.

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So all we have done up here is said, hey, typescript, we're going to have a location property, it

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will be an object that has these two properties, but we have not done 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.

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So we can try to initialize both Latin LNG will do Fakher address, not lattitude.

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I'll get a comma at the end of that line and then fakher dot address, dot longitude like so.

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Even then, I still see an error message if we mouseover this.

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You'll notice that it says.

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Expected right here, type string is not assignable to type No.

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So remember when we were looking at the documentation for the latitude and longitude or the type definition

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filed just a second ago, we saw the latitude and longitude where functions that returned strings,

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but we clearly said that latitude and longitude were going to be numbers.

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Once again, in my opinion, this is kind of an oversight by the Fakher people and they really should

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be returning numbers here.

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However, that's just how they built this library.

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So we need to take the strings that are returned by latitude and 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.

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We're going to use the pass float function just to make sure you are aware the passport function is

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built into JavaScript.

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It takes a string and returns a number that has a decimal value attached to it.

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So we can call parts float on both.

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And the air goes away because now we are signing a no to both latitude and longitude.

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All right, so that's pretty much it.

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Let's take a quick pause right here.

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

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So we'll see you in just a minute.