TypeScript

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TypeScript 入门教程

自定义工具类型

Creating Types from Types

替换类型中的属性

export type ReplaceFieldType<T, K extends keyof T, NewType> = {
  [P in keyof T]: P extends K ? NewType : T[P];
};

或者：

type Replace<T, K extends keyof T, V> = Omit<T, K> & { [P in K]: V };

提取类型中的泛型

export type ExtractGenericType<T> = T extends infer U ? U : T;

type Example1 = ExtractGenericType<Promise<string>>; // string
type Example2 = ExtractGenericType<Array<number>>; // number
type Example3 = ExtractGenericType<Set<boolean>>; // boolean
type Example4 = ExtractGenericType<string>; // string
type Example5 = ExtractGenericType<number>; // number