從文件夾ES6導入

Question

我正在學習JS，我有類似的東西。

//all inside folder reducers 

//reducer1.js 
export default reducer1 

//reducer2.js 
export default reducer2 

//index.js 
import reducer1 from './reducer1' 
import reducer2 from './reducer2' 
//then combine reducer 
export default index 

//outside folder reducers 
import reducer from './reducers' 

因爲./reducers只是一個文件夾，並且有3個文件，3出口默認裏面，我不明白這是怎麼工作的？它如何知道文件夾中的哪個導出默認值將被導入？

謝謝。

Answer 1

使用Webpack，當您導入文件夾時，模塊加載器將導入文件夾內的index.js。您正在index.js中導出索引，因此您在執行import reducer from './reducers'時會導入它。導入文件夾只是import reducer from reducers/index的簡寫。意思是兩個進口聲明是等價的。

總結起來，import reducer from './reducers'與import reducer from reducers/index相同。