javascript - Typescript:需要至少一个属性的类型

Question

这个问题已经有答案了:

How to create a Partial-like that requires a single property to be set (7 个回答)

已关闭 3 年前。

考虑我有以下类型:

type SomeType = {
  propOne: any;
  propTwo: any;
  propThree: any;
}

propOne为必填项，propTwo和propThree是可选的，但至少其中之一是必需的。如何定义具有该约束的类型？

// The following code is my expectation
let someVar1: SomeType = { propOne: 1, propTwo: "two" } //Okay
let someVar2: SomeType = { propOne: 1, propThree: "three" } //Okay
let someVar3: SomeType = { propOne: 1, propTwo: "two", propThree: "three" } //Okay
let someVar4: SomeType = { propOne: 1 } //Not Okay

Answer 1

即使在编辑后，您也可以使用相同的技巧:

type SomeType = {
  propOne: number;
  propTwo?: string;
  propThree?: string;
} & ({
  propTwo: string;
} | {
  propThree: string;
})

let someVar1: SomeType = { propOne: 1, propTwo: "two" } //Okay
let someVar2: SomeType = { propOne: 1, propThree: "three" } //Okay
let someVar3: SomeType = { propOne: 1, propTwo: "two", propThree: "three" } //Okay
let someVar4: SomeType = { propOne: 1 } //Not Okay

function f(s: SomeType) {
  let p1 = s.propOne; // number
  let p2 = s.propTwo; // string | undefined
  let p3 = s.propThree; // string | undefined
}

它强制您在声明时至少拥有一个属性，并且允许您在使用该类型的对象时同时使用该类型的两个属性。

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