module exports vs export default in Node js and ES6

Question

What is the difference between Node s module exports and ES6 s export default  I m trying to figure out why I get the     is not a constructor  error when I try to export default in Node js 6 2 2   What works   use strict  class SlimShady     constructor options        this  options   options        sayName         return  My name is Slim Shady             This works module exports   SlimShady   What doesn t work   use strict  class SlimShady     constructor options        this  options   options        sayName         return  My name is Slim Shady             This will cause the  SlimShady is not a constructor  error    if in another file I try  let marshall   new SlimShady    export default SlimShady

User · Answer

You need to configure babel correctly in your project to use export default and export const foo

npm install --save-dev @babel/plugin-proposal-export-default-from

then add below configration in .babelrc

"plugins": [ 
       "@babel/plugin-proposal-export-default-from"
      ]

User · Answer

Felix Kling did a great comparison on those two  for anyone wondering how to do an export default alongside named exports with module exports in nodejs module exports   new DAO   module exports initDAO   initDAO    append other functions as named export     now you have let DAO   require    helpers DAO       DAO by default is exported class or function DAO initDAO

User · Answer

The issue is with    how ES6 modules are emulated in CommonJS how you import the module   ES6 to CommonJS  At the time of writing this  no environment supports ES6 modules natively  When using them in Node js you need to use something like Babel to convert the modules to CommonJS  But how exactly does that happen   Many people consider module exports       to be equivalent to export default     and exports foo     to be equivalent to export const foo        That s not quite true though  or at least not how Babel does it   ES6 default exports are actually also named exports  except that default is a  reserved  name and there is special syntax support for it  Lets have a look how Babel compiles named and default exports      input export const foo   42  export default 21      output  use strict    Object defineProperty exports     esModule       value  true     var foo   exports foo   42  exports default   21     Here we can see that the default export becomes a property on the exports object  just like foo   Import the module  We can import the module in two ways  Either using CommonJS or using ES6 import syntax   Your issue  I believe you are doing something like   var bar   require    input    new bar      expecting that bar is assigned the value of the default export  But as we can see in the example above  the default export is assigned to the default property   So in order to access the default export we actually have to do  var bar   require    input   default    If we use ES6 module syntax  namely  import bar from    input   console log bar     Babel will transform it to   use strict    var  input   require    input     var  input2    interopRequireDefault  input    function  interopRequireDefault obj    return obj  amp  amp  obj   esModule   obj     default  obj       console log  input2 default     You can see that every access to bar is converted to access  default

[node.js] module.exports vs. export default in Node.js and ES6

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