typescript中interface约束不生效

Question

index.d.ts

export interface State {
    ua: string
}

state.ts

import { State } from "./index.d";
const state = (): State => ({
    ua: "other"
});
export default state;

mutations.ts

import * as TYPES from "./types";
import { State } from "./index.d";
const mutations = {
    /**
     * 保存浏览器类型
     */
    [TYPES.SAVE_UA](state: State, info: string) {
        // 这里使用State的interface有问题
        // (state as any).ua = info; 正常
        state.ua = info; // 报错 Property 'ua' does not exist on type 'State'.
    }
};
export default mutations;

我这个问题出在哪里了啊 我的State中明明 有ua这个属性的啊

Answer 1