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In this video, there's one last quick thing I want to mention, and that is one very special type that

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we haven't really discussed too much except in kind of passing.

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So at the bottom of this file, I want you to find one more function.

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I'm going to define a function called logger.

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This thing is going to take some message.

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That is a string.

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And then inside the function, I want you to just console log that message like so.

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So the only goal of this function is to call console log, and it does not actually return any value.

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So there's no return statement inside of here to annotate this fact as a return type.

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We'll put on Colen void like.

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So it's a void right here means that we have a function that's going to not return anything.

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Technically, a function that returns void can return null.

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And it can also return undefined, but effectively we use void right here to say there will be no return

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value from this function if we ever accidentally return something like so.

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Well, very quickly get an error message that says, hey, you can't return anything at all.

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Now, there's one other very special type associated with function return values as well.

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So I'm going to make one more function in here called throw error and throw ER will also take a message

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that is a string.

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And then any time we call this, I'm going to immediately throw a new air with that message like so.

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And just, you know, any time you throw an error, the function will technically not actually return

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anything.

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So to indicate that we could put on a Colen right here that says never, and that means that we are

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never going to actually reach the end of this function.

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So we're never going to execute the function completely at some point in time inside of here, we're

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going to throw an error and exit the function early without returning any value.

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Now, this is a really big court case, it's actually pretty darn rare that we're going to want to,

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like, intentionally throw in air like this, it's much more common for us to have some, like, actual

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return value in here, like, let's say if there is no message for some reason.

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Then we will throw in air.

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And then otherwise, we'll return like a. maybe just a message like so and so in this case, we would

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still imitate this as returning a string, even though it throws an error.

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So we only annotate a function with the type never when we really, truly never expect a function to

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return anything ever.

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If we at least expect it to return something eventually and only possibly through an error, that's

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totally fine.

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We're still going to annotate it with whatever we expect it to eventually return.

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And that does include the case where we return.

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Nothing like so.

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So in this case, we would still do a fallback to void because we are technically not returning anything

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and there's just a chance of us never reaching the end of the function.

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OK, so that's pretty much it.

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Let's take a quick pause right here and move on to our next subject.