Typescript 用法探索

generic_key.ts

/**
 * interface OOO { o: string }
 * key in keyof OOO
 * 等价于 key in 'o' | 'o'
 * 等价于 key in 'o'
 * 一定程度绕过直观上需要传入generic type的场景 function t<T,B>():<T<B>>{return {} as any}
 */

function geta<KEY extends string = 'data'>(aa: string) {
  const b: { [key in KEY]: any } = {
    [aa]: aa,
  } as any;
  return b;
}

const b: {
  ddd: any;
} = geta<'ddd'>('ddd');