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In this video I want to add in a couple little notes around syntax of interfaces.

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So once again when we define an interface we're going to list out all the different property names and

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types that we expect something that is a vehicle to have.

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We are not only limited to expressing primitive values inside of here we can instead express any different

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type.

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We want to inside of an interface.

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So for example let's say instead of the year property being a number we instead want this to be a more

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complex object like an instance of a date to do so I'm gonna replace no with simply date like so now

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in order for old Civic to be considered to be a vehicle in those so we've got an error down here.

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We have to update its definition.

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So instead of your being a simple No I'm going to instead assign it an instance of a date like so as

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soon as I do so that error down here goes away.

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So once again we are not limited to just basic values or primitive values inside of an interface definition

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we can assign any type inside there that we want that also includes functions.

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So let's say that we want to say that in order for old Civic to be considered to be a vehicle we want

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it to also have a function called summary.

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So in other words I want this object right here to have a property or a function called summary.

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And if we call it maybe it should return a String that summarizes some different facts about the vehicle

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to express that I'm going to add in another property on vehicle called summary like so and then instead

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of immediately putting in a set or a comma or C a colon right there I'll put in a set of parentheses

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and then a colon right after it and I'm going to label what I would expect the summary function to return.

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So in this case maybe it's going to return a String that summarizes some different facts about the car

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so this right here says that anything that wants to be a vehicle has to have a function called summary

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that returns a string if we then go back down to the bottom again you'll notice we have an error down

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here as well.

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So now it says that we do not have a summary property inside of old civic.

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So to fix this up we would have to add in a summary function that satisfies this type right here.

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So it has to be a function with no arguments that returns a string.

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And so we can add it on like so.

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So now to return some information about this vehicle we could return about like name is this name like

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so and again notice the yes 2015 template string here so I am using back tax.

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So now that my object has a summary function that returns a string it once again qualifies as being

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a vehicle so if I go back down to the bottom of the file again that era has now gone away and now inside

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of my print vehicle function rather than trying to pull off all these different properties one by one

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I can instead rely upon that summary function so I can call something like console dot log vehicle dot

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summary like so

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all right.

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So again just two notes here.

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First off we can use any type inside of our interface definition we want.

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We are not limited just to permanent values.

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Second important note is that inside of our interface definition we can express functions inside there

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as well so let's take a quick pause right here in the next video.

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I want to share two more important notes with you around basic syntax of interfaces so quick pause and

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I'll see you in just a minute.