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动态导入的返回类型是什么?

typescript2.4 typescript

-1

Tim Diekmann suresh madaparthi · 技术社区 · 6 年前

我有个文件必须 Promise :

export function load() {
    // ...
    return import(filename);
}

这个函数的返回类型是什么? Promise<any> 工作,但感觉很奇怪。我想把这个签名写为。

export function load() -> Promise<???>;

1 回复 | 直到 6 年前

1

10

Remo H. Jansen 6 年前

您需要使用导入类型和TypeScript 2.9

我的_模块.ts

export const user = { name: "John", age: 30 };
export const event = { name: "Birthday", date: new Date(1989, 13, 2) };

演示.ts

type ModuleType = typeof import("./my_module"); // This is the import type!

export function load(): Promise<ModuleType> {
    // ...
    return import("./my_module");
}

(async () => {
    const module = await load();
    console.log(module.user.age); // It works!
})();

tsconfig.json文件(增加供参考)

{
  "compilerOptions": {
    "target": "es5",
    "module": "commonjs",
    "lib": [
      "es2015",
      "dom"
    ], 
    "strict": true,  
    "esModuleInterop": true
  }
}

2

1

Ian Campbell 5 年前

type DynamicImportType = () => Promise<{ default: React.ComponentType<any>; }>;
type LazyComponentType = React.LazyExoticComponent<React.ComponentType<any>>;

const dynamicImport: DynamicImportType = () => import('./MyComponent');
const LazyComponent: LazyComponentType = React.lazy(dynamicImport);

资源

React.lazy
dynamic imports
搜索“ LazyExoticComponent the React types

3

1

unadlib 4 年前

counter.ts :

export class Counter {}

export const list = ['test'];

index.ts

type ImportClass<T, K extends keyof T> = T extends Record<K, infer S>
  ? S extends new (...args: any[]) => infer R
    ? R
    : never
  : never;

type ImportType<T, K extends keyof T> = T extends Record<K, infer R>
  ? R
  : never;

type Counter = ImportClass<typeof import('./counter'), 'Counter'>;

type List = ImportType<typeof import('./counter'), 'list'>;