你能声明一个允许在打字稿中使用未知属性的对象文字类型吗？

Question

Essentially I want to ensure that an object argument contains all of the required properties, but can contain any other properties it wants. For example:

function foo(bar: { baz: number }) : number {
    return bar.baz;
}

foo({ baz: 1, other: 2 });

But this results in:

Object literal may only specify known properties, and 'other' does not exist in type '{ baz: number; }'.

Answer 1

Yes, you can. Try this:

interface IBaz {
    baz: number;
    [key: string]: any;
}

function foo(bar: IBaz) : number {
    return bar.baz;
}

foo({ baz: 1, other: 2 });

Answer 2

Well, i hate answering my own questions, but the other answers inspired a little thought... This works:

function foo<T extends { baz: number }>(bar: T): void {
    console.log(bar.baz);
}

foo({baz: 1, other: 2});

Answer 3

If the known fields are coming from a generic type the way to allow wildcards is with T & {[key: string]: unknown} , any fields that are known must fit with the type's constraints and other fields are allowed (and considered type unknown )

Here is a sample:

type WithWildcards<T> = T & { [key: string]: unknown };

function test(foo: WithWildcards<{baz: number}>) {}

test({ baz: 1 }); // works
test({ baz: 1, other: 4 }); // works
test({ baz: '', other: 4 }); // fails since baz isn't a number

Then if you have a generic type T you can allow wildcard fields with WithWildCards<T>

Answer 4

This can be most easily accomplished by defining a type definition for the the function parameter. Here's an example with inline type definition:

function foo(bar: { baz: number }) : number {
    return bar.baz;
}

const obj = { baz: 1, other: 2 };

foo(obj);

Answer 5

If you want to allow unknown properties for the entire object, you can use Record

function doStuff(payload: Record<string|number, unknown>): Record<string|number, unknown> {
  return { anyProp: 'anyValue' }
}

Answer 6

当使用unknown类型时，您可以使用narrowing的概念来检查您希望从您正在经历的值中获得的类型，并根据您的需要操作这些值，例如

const messages: string []=Object.values(obj).map(val: unknown=>typeof obj==='object'?obj!['message']:obj)