使用 index.js 从“/文件夹”导入 javascript
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javascript import from '/folder' with index.js
提问by Jordan
I've noticed a few cases where I've seen something like the following:
我注意到一些案例，其中我看到了以下内容：
// /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...
}Notice the last "file" where we call import masterReducer from './reducers'- A few people seem to believe this should import the default exportfrom the index.js file.
注意我们调用的最后一个“文件” import masterReducer from './reducers'——有些人似乎认为这应该default export从 index.js 文件中导入。
Is this actually part of the specification? - my interpretation/question is that this is the result of many folks using WebPack v1 which translates importstatements into CommonJS-style requiresstatements? Or will this break in WebPack v2 with "official" import/exportsupport?
这实际上是规范的一部分吗？- 我的解释/问题是，这是许多人使用 WebPack v1 将import语句转换为 CommonJS 样式requires语句的结果？或者这会在具有“官方” import/export支持的WebPack v2 中中断吗？
回答by Bergi
Is this actually part of the specification?
这实际上是规范的一部分吗？
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 CommonJseither.
不。模块标识符（'./reducers'在您的情况下）如何解析为实际模块由模块加载器/捆绑器的实现决定，ES6 没有具体说明。而且它似乎也没有在CommonJs中指定。
This is just how node does it - when requiring a directory, it's index.jsfile will be used. Bundlers like browserifyor webpackfollowed this convention (for compat reasons).
这就是节点的工作方式 - 当需要目录时，index.js将使用它的文件。像捆扎机browserify或的WebPack遵循了这一约定（compat的原因）。
