ES6 module passthrough import/export editing experimentation

alt-submodule.js

// Load in our dependencies
import submodule from './submodule.js';

// Edit our pass-through content
// DEV: We can only modify mutable content on the submodule's keys
//   If we attempt to replace a direct key, then the edit won't pass through
//   submodule.bar = 'world'; // Works in this file, but doesn't pass through
submodule.bar.baz = 'hi';

// DEV: The following is a similarly acceptable way to pass-through edit
//   This will still work with `export * from` for all keys, including those not imported
// import {bar} from './submodule.js';
// bar.baz = 'hi';

// Perform re-export
// https://stackoverflow.com/a/38077264
export * from './submodule.js';

index.js

// Loads from `export default submodule;`
import submodule from './submodule.js';
console.log(submodule);

// Loads from `export {foo, bar};`
import {foo, bar} from './submodule.js';
console.log(foo, bar);

// Demonstration of loading still working for pass-through alteration
// DEV: `import` seems to be hoisted to top so comment out this line to see alteration/no alteration
// import {foo as foo2, bar as bar2} from './alt-submodule.js';
// console.log(foo2, bar2);

package.json

{
  "type": "module",
  "name": "gist-es6-pass-through-import-export",
  "version": "1.0.0",
  "description": "Explore ES6 passthrough import/export",
  "main": "index.js",
  "scripts": {
    "start": "node index.js",
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "Todd Wolfson <todd@twolfson.com> (http://twolfson.com/)",
  "license": "Unlicense",
  "dependencies": {},
  "devDependencies": {}
}

submodule.js

const foo = "foo";
const bar = {"bar": "bar"};

// We can export an object or similar as the entire default `import`
//    import submodule from './submodule.js';
const submodule = {foo, bar};
export default submodule;

// For called out key import, we need another format
// i.e. To use: import {foo, bar} from './submodule.js';
// We need an `export` call without `export default`

// Syntax doesn't allow exporting object
// export submodule;

// Instead must do explicit key export
export {foo, bar};