Javascript 使用强类型 Map
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Using strong typed Map
提问by BeetleJuice
I'm having trouble strong typing my Mapobjects with typescript 1.8.10. Here is an excerpt from core-jsdefining the Map interface:
我在Map用typescript 1.8.10. 以下是core-js定义 Map 接口的摘录：
interface Map<K, V> {
clear(): void;
delete(key: K): boolean;
forEach(callbackfn: (value: V, index: K, map: Map<K, V>) => void, thisArg?: any): void;
get(key: K): V;
has(key: K): boolean;
set(key: K, value?: V): Map<K, V>;
size: number;
}
I want to create a map that uses string keys and only ever stores values with the shape {name:string,price:number}. I tried declaring my object with:
我想创建一个使用字符串键并且只存储具有 shape 的值的地图{name:string,price:number}。我尝试用以下方法声明我的对象：
let oMap:Map<string,{name:string,price:number}> = new Map();
However, the compiler throws error TS2322: Type 'Map<{}, {}>' is not assignable to type 'Map<string, { name: string; price: number; }>'. Is there a way to take advantage of strong typing when using ES6 Mapobjects in typescript?
但是，编译器会抛出 error TS2322: Type 'Map<{}, {}>' is not assignable to type 'Map<string, { name: string; price: number; }>'。Map在打字稿中使用 ES6对象时，有没有办法利用强类型？
回答by zlumer
You need to provide generic types information to the created Maplike that:
您需要向创建的对象提供泛型类型信息，Map如下所示：
let oMap:Map<string,{name:string,price:number}> = new Map<string,{name:string,price:number}>();
And after that you can omit type declaration, leaving the job to compiler:
之后你可以省略类型声明，把工作留给编译器：
// oMap is correctly inferred to be Map<string,{name:string,price:number}>
let oMap = new Map<string,{name:string,price:number}>();
