m7yue / typescript-coding

typescript learning ...

type-challenges

关键字

• extends
• key of
• infer

技巧

• 裸类型: U extends U, [U] extends [U]
• 长度通过数组 ['length']
• number => string: ${T}
• I extends [infer F, ...infer Rest]
• S extends ${infer F}${infer Rest}
• as

   type PickByType<T, U> = {
     [P in keyof T as T[P] extends U ? P : never]: T[P]
   }

• -?: means required
• -readonly: means not readonly, mutable
• PropertyKey: 内置，string | number | symbol
• ThisType