package.json 和文件扩展名
【package.json and file extensions】
在一个包中，package.json "type" 字段定义了 Node.js 应该如何解释 .js 文件。如果 package.json 文件没有 "type" 字段，.js 文件将被视为 CommonJS。
【Within a package, the package.json "type" field defines how
Node.js should interpret .js files. If a package.json file does not have a
"type" field, .js files are treated as CommonJS.】
'package.json' '类型''的'“模块”值告诉Node.js解释“.js” 该包内的文件使用ES 模块语法。
【A package.json "type" value of "module" tells Node.js to interpret .js
files within that package as using ES module syntax.】
"type" 字段不仅适用于初始入口点 (node my-app.js)，还适用于通过 import 语句和 import() 表达式引用的文件。
【The "type" field applies not only to initial entry points (node my-app.js)
but also to files referenced by import statements and import() expressions.】
// my-app.js, treated as an ES module because there is a package.json
// file in the same folder with "type": "module".
import './startup/init.js';
// Loaded as ES module since ./startup contains no package.json file,
// and therefore inherits the "type" value from one level up.
import 'commonjs-package';
// Loaded as CommonJS since ./node_modules/commonjs-package/package.json
// lacks a "type" field or contains "type": "commonjs".
import './node_modules/commonjs-package/index.js';
// Loaded as CommonJS since ./node_modules/commonjs-package/package.json
// lacks a "type" field or contains "type": "commonjs". 以 .mjs 结尾的文件总是作为 ES 模块 加载，无论最近的父级 package.json 是什么。
【Files ending with .mjs are always loaded as ES modules regardless of
the nearest parent package.json.】
以 .cjs 结尾的文件总是作为 CommonJS 加载，无论最近的父级 package.json 是什么。
【Files ending with .cjs are always loaded as CommonJS regardless of the
nearest parent package.json.】
import './legacy-file.cjs';
// Loaded as CommonJS since .cjs is always loaded as CommonJS.
import 'commonjs-package/src/index.mjs';
// Loaded as ES module since .mjs is always loaded as ES module. .mjs 和 .cjs 扩展名可以在同一个包中混合使用不同类型：
【The .mjs and .cjs extensions can be used to mix types within the same
package:】