Typescript：需要至少一个属性的类型

Question

考虑我有以下类型：

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

是propOne必需的，propTwo并且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

You can use the same trick even after your edit:

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
}

It forces you to have at least one property at declaration time, and it allows you to use both properties of the type when using objects of that type.

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