From e3c3e8ee2d5db819dd24daa239c682a8de76f474 Mon Sep 17 00:00:00 2001 From: panxiandiao Date: Fri, 12 Jun 2020 16:01:35 +0800 Subject: [PATCH] fix anyProperty fix anyProperty --- basics/type-of-object-interfaces.md | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-) diff --git a/basics/type-of-object-interfaces.md b/basics/type-of-object-interfaces.md index 34d2ca4d..30fff1bb 100644 --- a/basics/type-of-object-interfaces.md +++ b/basics/type-of-object-interfaces.md @@ -143,23 +143,20 @@ let tom: Person = { gender: 'male' }; -// index.ts(3,5): error TS2411: Property 'age' of type 'number' is not assignable to string index type 'string'. -// index.ts(7,5): error TS2322: Type '{ [x: string]: string | number; name: string; age: number; gender: string; }' is not assignable to type 'Person'. -// Index signatures are incompatible. -// Type 'string | number' is not assignable to type 'string'. -// Type 'number' is not assignable to type 'string'. +// index.ts(3,5): error TS2411: Property 'age' of type 'number | undefined' is not assignable to string index type 'string'. +// index.ts(7,5): error TS2322: Type '{ name: string; age: number; gender: string; }' is not assignable to type 'Person'. +// Property 'age' is incompatible with index signature. +// Type 'number' is not assignable to type 'string'. ``` -上例中，任意属性的值允许是 `string`，但是可选属性 `age` 的值却是 `number`，`number` 不是 `string` 的子属性，所以报错了。 - -另外，在报错信息中可以看出，此时 `{ name: 'Tom', age: 25, gender: 'male' }` 的类型被推断成了 `{ [x: string]: string | number; name: string; age: number; gender: string; }`，这是联合类型和接口的结合。 +上例中，任意属性的值允许是 `string`，但是可选属性 `age` 的值却是 `number` 或者 `undefined`，它们不是 `string` 的子属性，所以报错了。 一个接口中只能定义一个任意属性。如果接口中有多个类型的属性，则可以在任意属性中使用联合类型： ```ts interface Person { name: string; age?: number; - [propName: string]: string | number; + [propName: string]: string | number | undefined; } let tom: Person = {