vue3 Composition api 变量类型推断问题 - V2EX
V2EX = way to explore
V2EX 是一个关于分享和探索的地方
Sign Up Now
For Existing Member  Sign In
webberone

vue3 Composition api 变量类型推断问题

  •  
  •   webberone Nov 19, 2020 2833 views
    This topic created in 1988 days ago, the information mentioned may be changed or developed.
    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 replies    2020-11-19 15:42:17 +08:00
    9ki
        1
    9ki  
       Nov 19, 2020
    ```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
       Nov 19, 2020
    @9ki 了解了,灰常感谢
    About     Help     Advertise     Blog     API     FAQ     Solana     850 Online   Highest 6679       Select Language
    创意工作者们的社区
    World is powered by solitude
    VERSION: 3.9.8.5 28ms UTC 19:48 PVG 03:48 LAX 12:48 JFK 15:48
    Do have faith in what you're doing.
    ubao msn snddm index pchome yahoo rakuten mypaper meadowduck bidyahoo youbao zxmzxm asda bnvcg cvbfg dfscv mmhjk xxddc yybgb zznbn ccubao uaitu acv GXCV ET GDG YH FG BCVB FJFH CBRE CBC GDG ET54 WRWR RWER WREW WRWER RWER SDG EW SF DSFSF fbbs ubao fhd dfg ewr dg df ewwr ewwr et ruyut utut dfg fgd gdfgt etg dfgt dfgd ert4 gd fgg wr 235 wer3 we vsdf sdf gdf ert xcv sdf rwer hfd dfg cvb rwf afb dfh jgh bmn lgh rty gfds cxv xcv xcs vdas fdf fgd cv sdf tert sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf shasha9178 shasha9178 shasha9178 shasha9178 shasha9178 liflif2 liflif2 liflif2 liflif2 liflif2 liblib3 liblib3 liblib3 liblib3 liblib3 zhazha444 zhazha444 zhazha444 zhazha444 zhazha444 dende5 dende denden denden2 denden21 fenfen9 fenf619 fen619 fenfe9 fe619 sdf sdf sdf sdf sdf zhazh90 zhazh0 zhaa50 zha90 zh590 zho zhoz zhozh zhozho zhozho2 lislis lls95 lili95 lils5 liss9 sdf0ty987 sdft876 sdft9876 sdf09876 sd0t9876 sdf0ty98 sdf0976 sdf0ty986 sdf0ty96 sdf0t76 sdf0876 df0ty98 sf0t876 sd0ty76 sdy76 sdf76 sdf0t76 sdf0ty9 sdf0ty98 sdf0ty987 sdf0ty98 sdf6676 sdf876 sd876 sd876 sdf6 sdf6 sdf9876 sdf0t sdf06 sdf0ty9776 sdf0ty9776 sdf0ty76 sdf8876 sdf0t sd6 sdf06 s688876 sd688 sdf86