TypeScript - 특이 케이스

• [[Cross instance member access from subclass]]

Array와 Tuple중 Array가 먼저 infer되므로 as const 활용 해야함

keyof는 intersection처럼 작동한다.

interface AMap {
  'AAA': never;
}


interface BMap {
  'B': never;
  'BB': never;
  'BBB': string;
}

interface CMap {
  'C': number;
  'CC': string;
  'CCC': Function;
  'CCCC': Map<any, any>;
}

export type ABCEventMap = AMap & BMap & CMap;
export type ABCType = keyof ABCMap; // keyof AMap | keyof BMap | keyof CMap

제너릭에 타입 파라미터 사용시 추론이 안되는 문제

Argument of Type 'InterfaceDerived' is not assinable to parameter of type 'interfaceBase'

• https://timdeschryver.dev/blog/argument-of-type-interface-is-not-assignable-to-parameter-of-type-interface
• https://stackoverflow.com/questions/46068834/typescript-generics-argument-of-type-x-is-not-assignable-to-parameter-of-type

• static implementation을 강제하는 방법은 없다
  • https://github.com/microsoft/TypeScript/issues/34516
• module scope 멤버 접근자

https://stackoverflow.com/questions/51808160/keyof-inferring-string-number-when-key-is-only-a-string

interface XMap {
    [key: string]: any;
}

type X = keyof XMap; // number | string