Manipulate String Literals Using Type Helpers
We'll start off with the Record type, passing it Event and string. However, this time we'll also add the Uppercase type helper around Event:
The Uppercase string manipulation type is built into TypeScript, and in this case is applied to each member of the union that is being mapped over.
Transcript
0:00 The solution is pretty intuitive. We look at the previous solution that we had and it was a record with these TemplateLiteralKeys and turning them into strings.
0:10 We're doing the same thing here, except we're not having to do any union stuff, except which is add an uppercase string literal type to them. This is a type helper that's intrinsic to the language and lets you turn a string into an uppercase string.
0:26 We can say, type UppercaseEvent = Uppercase and then Event. What we end up with is it maps over each member of the union and you end up with LOG_IN, LOG_OUT, SIGN_UP.
0:38 There are a few of these. We can have, Capitalized, which is nice. We can also have LowercaseEvent, which doesn't do anything in this case, but if we had a "LOG_OUT" inside here, then it would turn it into the lowercase version. There are a bunch of others as well.
0:55 I wanted to give you a brief insight into these. There's plenty of documentation on them and they're all pretty simple to understand. Yeah, TypeScript gives you these out-of-the-box helpers to even do more crazy manipulation of string literals. Very cool.
