I was testing circular dependency with commonjs.

//index.js
console.log('main starting');
const a = require('./a.js');
const b = require('./b.js');
console.log('in main, a.done = %j, b.done = %j', a.done, b.done);

//a.js
console.log('a starting');
exports.done = false;
const b = require('./b.js');
console.log('in a, b.done = %j', b.done);
exports.done = true;
console.log('a done');

//b.js
console.log('b starting');
exports.done = false;
const a = require('./a.js');
console.log('in b, a.done = %j', a.done);
exports.done = true;
console.log('b done');

The result was

// output
main starting
a starting
b starting
in b, a.done = false
b done
in a, b.done = true
a done
in main, a.done = true, b.done = true

So index import a and a import b

b try to import a but a is not finished so a return unfinished module.

OK fine, I understood.

But what about esmodule syntax ?

I reproduced code like this.

//index.js

console.log('main starting');
import a from './a.js';
import b from './b.js';
console.log('in main, a.done = %j, b.done = %j', a.done, b.done);

//a.js
console.log('a starting');
export let done = false;
import {done as B_done}  from './b.js';
console.log('in a, b.done = %j', B_done);
done = true;
console.log('a done');
export default {
    done
}

//b.js
console.log('b starting');
export let done = false;
import {done as A_done} from './a.js';
console.log('in b, a.done = %j', A_done);
done = true;
console.log('b done');
export default {
    done
}

But the result was changed.

ReferenceError: Cannot access 'A_done' before initialization

This error occrued.

Why is it giving me a different result than commonjs ?

Doesn't esmodule return unfinished modules?

You can actually find this code sample in here