This is a proof of concept post, personally I do not find any use of this, yet Typescript recursion stop at 49th or 999th loop type CreateArrayWithLengthX< LENGTH extends number, ACC extends unknown[] = [], > = ACC['length'] extends LENGTH ? ACC…

Before TS 4.8, obtaining value type for path A/${number} of { A: Record<number, boolean> } is possible, that is type B = DeepValue<A/${number}> // boolean however it is impossible to get the value type for path A/${123} of { A: { 123: boolean } }, type B = DeepValue<A/${123}> //…

background: type equality check Typescript power users often find themselves in the need of type equality check, and this is the usual way to do it export type IsEqual<T, U> = (<G>() => G extends T ? 1 : 2) extends (<G>() => G extends U ? 1…

I made a library that solves Firebase Realtime Database typing problems. It is the sister project of my other project, FirelordJS (for Firestore) And similar to FirelordJS, FireSageJS comes with an extreme type safety mechanism without straying from the official library API. You get the best of both worlds: low…

type A = {name: string} type B = {name: number} type C = {name: string , age:number} type D = {name: string , age:string} type E = {name: string , address:string} type Prettify<T extends Record<string, unknown>> = { [K in keyof T]: T[K] } type UnionKeysAndMakeUncommonKeysOptional< T extends Record<string, unknown>[]…

type A = {[x:string]:string} type B = keyof A // string | number // ^? const A:A = {a:"abc",[1]:"xyz"} type C = keyof A & string // string // ^? playground normally this will not cause any issue, because number key in javascript will coerce into string key however this…

because Typescript has no negate type and without it, string cannot cover key that are not a1 and a2, string has to cover all keys. type A = {[x:string]:1, a1:1, a2:2} // error: Property 'a2' of type '2' is not assignable to 'string' index type '1'. type a = A['something']…

In this post we are going to try to find nth root of x where x and n are both numeric literal types to do this, we need to utilize exponentiation type with a slight modification: type CreateArrayWithLengthX< LENGTH extends number, ACC extends unknown[]…

In this post, we are going to try to raise x to the power of n x and n are both numeric literal types to do this, we need to utilize multiplication type with a slight modification: type CreateArrayWithLengthX< LENGTH extends number, ACC extends…