How do I define a typescript type with a repeating structure？-CodePudding

I have a type that looks something like this:

type Location=`${number},${number};${number},${number};...`

Is there a Utility type like Repeat<T> that can do this for me? like this:

type Location=Repeat<`${number},${number};`>

CodePudding user response：

You can directly choose type string if you want as:

type myLocation = string;
const myLocation: myLocation = "123123123";

console.log(myLocation);

else if you want to narrow it down then better to declare it const as:

const myLocation = "123123123";
console.log(myLocation);

then your type will be the value of the myLocation

CodePudding user response：

I don't think there is a way to define an infinite repeating pattern for a type that you use on variable declaration.

However, a type guard on a function can check that a string matches an infinite pattern, like so (playground):

type MatchesPattern<Pattern extends string, Current extends string> = Current extends `` ? string : (Current extends `${Pattern}${infer Rest}` ? MatchesPattern<Pattern, Rest> : never);

type LocationPattern = `${number},${number};`;

declare function onlyAcceptsLocation<L extends string & IsLocation, IsLocation = MatchesPattern<LocationPattern, L>>(location: L): void;

onlyAcceptsLocation("12,34;56,78;"); //