vue3 Composition api 变量类型推断问题 - V2EX
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webberone
V2EX    Vue.js

vue3 Composition api 变量类型推断问题

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  •   webberone 2020-11-19 14:09:18 +08:00 2665 次点击
    这是一个创建于 1855 天前的主题,其中的信息可能已经有所发展或是发生改变。
    用 vue3 + ts 开发过程中,用 const root = ref(null)创建一个模板引用,编译器会提示创建出来的 root 类型是 Ref(null),但是有的项目提示类型是 Ref(any),这是什么原因呀
    2 条回复    2020-11-19 15:42:17 +08:00
    9ki
        1
    9ki  
       2020-11-19 14:46:22 +08:00
    ```typescript
    export declare function ref<T extends object>(value: T): T extends Ref ? T : Ref<UnwrapRef<T>>;

    export declare function ref<T>(value: T): Ref<UnwrapRef<T>>;

    export declare function ref<T = any>(): Ref<T | undefined>;
    ```
    上面是 vue3 ref 的类型声明
    如果你在 `tsconfig.json` 开启了 `strictNullChecks ` 则 ts 会区分 null 和 undefined,否则则不区分,而是当成 any 处理
    所以:如果你没有开启,那么传了 null 则会匹配到
    ``` export declare function ref<T extends object>(value: T): T extends Ref ? T : Ref<UnwrapRef<T>>; ```

    所以最终为 any
    webberone
        2
    webberone  
    OP
       2020-11-19 15:42:17 +08:00
    @9ki 了解了,灰常感谢
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