流程：将导入的对象类型中的键设为可选

Question

我想从外部模块导入一个随机对象并使用它们的流类型：

export type randomType = {
    a: string,
    b: boolean
}

我想将 randomType 导入我的库，但我想将 b 设为可选

import { randomType } from 'randomModule';
// pseudo flow code:
type shrinkedRandomType = randomType - {b: boolean}
// How can I make this in flow so it equals this?
type shrinkedRandomType = {
    a: string,
    b?: boolean
}
// or even 
type shrinkedRandomType = {
    a: string
}

Answer 1

传播运算符来救援！

如果您不熟悉扩展运算符，look it up on MDN

否则，方法如下：

type randomType = {
    a: string,
    b: boolean
}

type shrinkedRandomType = {
    ...randomType,
    b?: boolean
}

// Perfectly valid
let test:shrinkedRandomType = {
 a: "Hi"
}