Supporting Common JS Named Exports using ES Module Imports

Hello & good day! Since the latest release, the import { version } from './package.json and other imports from JSON files is broken for Node.JS module resolution.

import { version } from '../package.json'
console.log(version)

Version: v20190301 Built on: 2019-03-05 23:14 with

-jar node_modules/google-closure-compiler-java/compiler.jar 
--compilation_level ADVANCED 
--module_resolution NODE
--js t/package.js package.json

produces console.log("0.0.1-alpha");

Whereas the update has now made it not possible 😦

Exit code 1                                         
t/package.js:2: ERROR - variable null is undeclared
console.log(version)
            ^^^^^^^

1 error(s), 0 warning(s)

I’m now wondering if importing JSON files is actually part of Ecma6 but I don’t see why it shouldn’t be for at least for Node Module resolution in Closure.

If works with require and --process_common_js_modules btw:

const { version } = require('../package.json')
console.log(version)

[ChadKillingsworth]

I realize the frustration here - it’s pretty much felt by the entire dev community right now. We got here directly because a transpiler (Babel) made decisions that weren’t actually able to be natively implemented.

However If Closure Compiler deviates from the current spec, we’ll be making the problem worse - not better. Then when the spec gets figured out, we’ll have to migrate our dev community to the proper way and that can be painful too.

Just as a note, the following should work just fine:

import pkg from '../package.json'
console.log(pkg.version)

It’s only the destructuring style of import that has the issue.

[ChadKillingsworth]

This is by design. The interop between CommonJS and ES Modules is defined by NodeJS and has gone through several iterations (there’s yet a new one coming). The last supported version stated that CommonJS modules only have a default export when referenced from an ES Module. CommonJS does not have named exports.

The latest proposal and work effort can be found at https://github.com/nodejs/modules/blob/master/doc/plan-for-new-modules-implementation.md

This is a complex issue and at this point I’d really like to see that this version will actually happen before implementing it in Closure-Compiler. Also - it’s likely to include breaking changes so this could be a bit painful. The good news is that the Node community seems to be taking all the developer backlash to the last version to heart and is working hard to address that in the newest version.