新的javascript ES6模块术语中的合格和不合格导入有什么区别？

Question

I came across this distinction which wasn't explained well in ExploringJS

Qualified and unqualified imports work the same way (they are both indirections)

What is the distinction and therefore what does this statement mean?

Answer 1

Strictly speaking, there's no such thing as qualified/unqualified imports in JavaScrpit. Those terms were used in the book 'Exploring ES6' by Dr. Axel Rauschmayer in the context of cyclic dependencies, and roughly mean:

Unqualified imports (directly import a part of a module):

CommonJS

var foo = require('a').foo // doesn't work with cyclic dependencies

ES2015

import {foo} from 'a' // can work with cyclic dependencies*

Qualified imports (import the whole module as a namespace):

CommonJS

var a = require('a')
function bar() {
  a.foo() // can work with cyclic dependencies*
}
exports.bar = bar

ES2015

import * as a from 'a'
export function bar() {
  a.foo() // can work with cyclic dependencies*
}

In ES2015 default imports can also be qualified imports (although some people disagree) if they serve as a namespace:

export default {
  fn1,
  fn2
}

*with cyclic dependencies, you can't access imports in the body of a module:

import {foo} from 'a' // 'a' is a cyclic dependency
foo() // doesn't work