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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 to the bottom of this file I want to

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define 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 that is a string and then inside the function I want to just

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console log that message like so so the only goal of this function is to call console log and it does

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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 we'll put on colon

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void like 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 and it can also return undefined but effectively

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we use void right here to say there will be no return value from this function if we ever accidentally

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return something like So we'll very quickly get an error message that says hey you can't return anything

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at all.

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

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So going to make one more function in here called throw Error and throw Error will also take a message

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that is a string and then anytime we call this I'm going to immediately throw a new air with that message

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like so and just you know any time you throw an error the function well technically not actually return

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anything so to indicate that we could put on a colon right here that says never.

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And that means that we are never going to actually reach the end of this function so we're never going

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to execute the function completely.

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At some point time inside of here we're going to throw an error and exit the function early without

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returning any value.

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Now this is a really big corner case.

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It's actually pretty darn rare that we're going to want to like intentionally throw in error like this.

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It's much more common for us to have some like actual return value in here like let's say if there is

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no message for some reason then we will throw an error and then otherwise we'll return like an hour

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maybe just the message like so.

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And so in this case we would still annotate 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 return

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anything ever.

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

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fine 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 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 okay.

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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.