使用index.js从'/ folder'导入javascript [英] javascript import from '/folder' with index.js

问题描述

我注意到有几个案例我见过以下内容：

I've noticed a few cases where I've seen something like the following:

// /reducers/reducer1.js
export default function reducer1(state = {}, action){
  // etc...
}
  
// /reducers/reducer2.js
export default function reducer2(state = {}, action){
  // etc...
}

// /reducers/index.js
import { combineReducers } from 'redux';
import reducer1 from './reducer1';
import reducer2 from './reducer2';

export default combineReducers({
  reducer1,
  reducer2
})
  
// /store.js
import masterReducer from './reducers';

export default function makeStore(){
  // etc...
}

注意我们调用的最后一个文件从'./reducers'中导入masterReducer - 有些人似乎认为这应该导入 index.js文件中的默认导出。

Notice the last "file" where we call import masterReducer from './reducers' - A few people seem to believe this should import the default export from the index.js file.

这实际上是规范的一部分？ - 我的解释/问题是，这是许多人使用WebPack v1的结果，它将 import 语句翻译成CommonJS风格的需要陈述？或者这将在WebPack v2中以官方 import / export 支持？

Is this actually part of the specification? - my interpretation/question is that this is the result of many folks using WebPack v1 which translates import statements into CommonJS-style requires statements? Or will this break in WebPack v2 with "official" import/export support?

推荐答案

这实际上是规范的一部分吗？

Is this actually part of the specification?

没有。如何将模块标识符（在您的情况下为'./ reducers'）解析为实际模块，由模块加载器/捆绑器实现，而不是由ES6指定。它似乎也没有在 CommonJs 中指定。

No. How module identifiers ('./reducers' in your case) are resolved to the actual modules is left to the implementation of the module loader/bundler, it's not specificed by ES6. And it doesn't seem to be specified in CommonJs either.

这就是节点的工作方式 - 当需要一个目录时，它将使用 index.js 文件。像 browserify 或 webpack 遵循此约定（出于比较原因）。

This is just how node does it - when requiring a directory, it's index.js file will be used. Bundlers like browserify or webpack followed this convention (for compat reasons).

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