导入映射 | Node.js API 文档

¥Import maps

前面的两个示例定义了 load 钩子。这是 resolve 钩子的示例。这个钩子模块读取一个 import-map.json 文件，该文件定义了要覆盖其他 URL 的说明符（这是 "导入映射" 规范的一小部分的非常简单的实现）。

¥The previous two examples defined load hooks. This is an example of a resolve hook. This hooks module reads an import-map.json file that defines which specifiers to override to other URLs (this is a very simplistic implementation of a small subset of the "import maps" specification).

// import-map-hooks.js
import fs from 'node:fs/promises';

const { imports } = JSON.parse(await fs.readFile('import-map.json'));

export async function resolve(specifier, context, nextResolve) {
  if (Object.hasOwn(imports, specifier)) {
    return nextResolve(imports[specifier], context);
  }

  return nextResolve(specifier, context);
}

有了这些文件：

¥With these files:

// main.js
import 'a-module';

// import-map.json
{
  "imports": {
    "a-module": "./some-module.js"
  }
}

// some-module.js
console.log('some module!');

运行 node --import 'data:text/javascript,import { register } from "node:module"; import { pathToFileURL } from "node:url"; register(pathToFileURL("./import-map-hooks.js"));' main.js 应打印 some module!。

¥Running node --import 'data:text/javascript,import { register } from "node:module"; import { pathToFileURL } from "node:url"; register(pathToFileURL("./import-map-hooks.js"));' main.js should print some module!.