node.js module.exports & exports & module.export all in one

node.js module.exports & exports & module.export all in one

cjs

const log = console.log;

log(`exports`, exports);
log(`module`, module);

// TypeError: Cannot set property 'a' of undefined
// module.export.a = 1;
// module.export.b = 2;
// module.export.c = 3;
// module.export.d = 4;

// 自定义属性 umd ✅
module.umd = {
  a: 1,
  b: 2,
  c: 3,
  d: 4,
};
// 自定义属性 export ✅
module.export = {
  a: 1,
  b: 2,
  c: 3,
  d: 4,
};

exports.a = 11;
exports.b = 22;
exports.c = 33;
exports.d = 44;

// module.exports 覆盖 exports
module.exports = { c: 333 };
module.exports.d = 444;

log(`\nexports`, exports);
log(`module`, module);


/*


exports { a: 11, b: 22, c: 33, d: 44 }
module Module {
  id: '.',
  path: '/Users/xgqfrms-mbp/Documents/GitHub/umd-npm-package/src',
  exports: { c: 333, d: 444 },
  parent: null,
  filename: '/Users/xgqfrms-mbp/Documents/GitHub/umd-npm-package/src/export.js',
  loaded: false,
  children: [],
  paths: [
    '/Users/xgqfrms-mbp/Documents/GitHub/umd-npm-package/src/node_modules',
    '/Users/xgqfrms-mbp/Documents/GitHub/umd-npm-package/node_modules',
    '/Users/xgqfrms-mbp/Documents/GitHub/node_modules',
    '/Users/xgqfrms-mbp/Documents/node_modules',
    '/Users/xgqfrms-mbp/node_modules',
    '/Users/node_modules',
    '/node_modules'
  ],
  umd: { a: 1, b: 2, c: 3, d: 4 },
  export: { a: 1, b: 2, c: 3, d: 4 }
}
*/

module.exports vs exports

const log = console.log;

const app = (datas = [], debug = false) => {
  log(`args =`, datas);
};

const test = `abc`;

// 👍✅ default export (const app = require(`./app`);)
module.exports = app;

module.exports.test = test;

// ✅
// module.exports.app = app;

// ✅
// module.exports = {
//   app,
// };

log(`exports =`, exports);
log(`module.exports =`, module.exports);
// exports = {}
// module.exports = [Function: app] { test: 'abc' }
// log(`module`, module);

const log = console.log;

// 🎉 import default module
const app = require(`./app`);
// const app, {test} = require(`./app`);

log(`\napp =`, app, app.app);
app();
// app = [Function: app] undefined
// args = []

log(`test =`, app.test);
// test = abc

const log = console.log;

const app = (datas = [], debug = false) => {
  log(`args =`, datas);
};

const test = `abc`;

// 👎❌
// exports = app;

// ✅ module export (const { app, } = require(`./app`);)
exports.app = app;

exports.test = test;

log(`exports =`, exports);
log(`module.exports =`, module.exports);
// exports = { app: [Function: app], test: 'abc' }
// module.exports = { app: [Function: app], test: 'abc' }
// log(`module`, module);

const log = console.log;

// 🔖 imports multi modules
const { app, test, } = require(`./app`);

log(`\napp =`, app);
app();
// app = [Function: app]
// args = []

log(`test =`, test);
// test = abc

exports = module.exports

✅ module.exports 与 exports 指向同一个Object 引用

https://blog.tableflip.io/the-difference-between-module-exports-and-exports

"use strict";

/**
 *
 * @author xgqfrms
 * @license MIT
 * @copyright xgqfrms
 * @created 2020-10-01
 * @modified
 *
 * @description
 * @difficulty Easy Medium Hard
 * @complexity O(n)
 * @augments
 * @example
 * @link
 * @solutions
 *
 * @best_solutions
 *
 */

const log = console.log;

// ✅ module.exports 与 exports 指向同一个Object 引用

// SyntaxError: Identifier 'module' has already been declared
// module = {
//   exports: {},
//   //others
// };
// // {exports: {…}}

// module.exports;
// // {}

// exports = module.exports;
// // {}

// exports.a = `a`;

// module.exports.a = `aa`;
// module.exports.b = `b`;

// log(`exports =`, exports);
// log(`module.exports =`, module.exports);

/*

exports = { a: 'aa', b: 'b' }
module.exports = { a: 'aa', b: 'b' }

*/

const test = () => {
  const module = {
    exports: {},
    //others
  };
  // {exports: {…}}
  module.exports;
  // {}
  const exports = module.exports;
  // {}
  exports.a = `a`;
  module.exports.a = `aa`;
  module.exports.b = `b`;
  log(`exports =`, exports);
  log(`module.exports =`, module.exports);
}
test();

/*

exports = { a: 'aa', b: 'b' }
module.exports = { a: 'aa', b: 'b' }

*/

refs

https://gist.github.com/xgqfrms/b69677e524d4c4e154fef6342914eb00

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