exporting multiple modules in react.js

Question

New to react.js and trying to following tutorial. Unfortunately the code given in the page didn't work. webpack complained

ERROR in ./App.jsx
Module build failed: SyntaxError: Only one default export allowed per module.

Wonder how to fix it. Thanks.

=== App.jsx====

import React from 'react';
import ReactDOM from 'react-dom';
import { Router, Route, Link, browserHistory, IndexRoute  } from 'react-router'

class App extends React.Component {
   render() {
      return (
         <div>
            <ul>
               <li><Link to = "/home">Home</Link></li>
               <li><Link to = "/about">About</Link></li>
               <li><Link to = "/contact">Contact</Link></li>
            </ul>

           {this.props.children}
         </div>
      )
   }
}

export default App;

class Home extends React.Component {
   render() {
      return (
         <div>
            <h1>Home...</h1>
         </div>
      )
   }
}

export default Home;

class About extends React.Component {
   render() {
      return (
         <div>
            <h1>About...</h1>
         </div>
      )
   }
}

export default About;

class Contact extends React.Component {
   render() {
      return (
         <div>
            <h1>Contact...</h1>
         </div>
      )
   }
}

export default Contact;

=== main.js ===

import React from 'react';
import ReactDOM from 'react-dom';
import App from './App.jsx';

ReactDOM.render(<App/>, document.getElementById('app'));

UPDATE1

I commented out all the export default and added the following at the end

module.exports = {
    App: App,
    Home: Home,
    About: About,
    Contact: Contact
}

Now there is no compile error but the web page is a blank. I am not sure what is wrong here.

Possible duplicate of Multiple React components in a single module — Chris
– Chris, Commented Sep 4, 2017 at 15:16
@Chris I checked out the link and tried to make some changes and it is still not working, see the update1 section. Thx. — packetie
– packetie, Commented Sep 4, 2017 at 15:21

Tomasz Mularczyk · Accepted Answer · 2018-10-06 11:48:58Z

206

You can have only one default export which you declare like:

export default App; or export default class App extends React.Component {...

and later do import App from './App'

If you want to export something more you can use named exports which you declare without default keyword like:

export {
  About,
  Contact,
}

or:

export About;
export Contact;

or:

export const About = class About extends React.Component {....
export const Contact = () => (<div> ... </div>);

and later you import them like:

import App, { About, Contact } from './App';

EDIT:

There is a mistake in the tutorial as it is not possible to make 3 default exports in the same main.js file. Other than that why export anything if it is no used outside the file?. Correct main.js :

import React from 'react';
import ReactDOM from 'react-dom';
import { Router, Route, Link, browserHistory, IndexRoute  } from 'react-router'

class App extends React.Component {
...
}

class Home extends React.Component {
...
}


class About extends React.Component {
...
}


class Contact extends React.Component {
...
}


ReactDOM.render((
   <Router history = {browserHistory}>
      <Route path = "/" component = {App}>
         <IndexRoute component = {Home} />
         <Route path = "home" component = {Home} />
         <Route path = "about" component = {About} />
         <Route path = "contact" component = {Contact} />
      </Route>
   </Router>

), document.getElementById('app'))

EDIT2:

another thing is that this tutorial is based on react-router-V3 which has different api than v4.

edited Oct 6, 2018 at 11:48

answered Sep 4, 2017 at 15:38

Tomasz Mularczyk

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13 Comments

packetie Over a year ago

Thanks for the tip, the problem is, I don't where the import App etc are called in the compiler (webpack). Any ideas?

Tomasz Mularczyk Over a year ago

I don't know that, but why would you be concerned about it? In order to make your code work you must have one default export and others (if in the same file) have to be named.

packetie Over a year ago

I am very new to this and trying to follow the tutorial. All the previous sections in the tutorial are fine. Any idea how to make the route work as shown there?

Tomasz Mularczyk Over a year ago

I believe there is mistake in the tutorial because it is not possible to make 3 default exports in the same main.js file. Please first move each component class to distinct file like Contact.jsx etc. and in each file make export default Contact; etc.

packetie Over a year ago

Moved the sections of Home, About, Contact into their .jsx files. Don't see a compile error but the web page is blank. Any ideas?

|

iboss · Accepted Answer · 2017-09-04 15:40:43Z

7

When you

import App from './App.jsx';

That means it will import whatever you export default. You can rename App class inside App.jsx to whatever you want as long as you export default it will work but you can only have one export default.

So you only need to export default App and you don't need to export the rest.

If you still want to export the rest of the components, you will need named export.

https://developer.mozilla.org/en/docs/web/javascript/reference/statements/export

edited Sep 4, 2017 at 15:40

answered Sep 4, 2017 at 15:35

iboss

4966 silver badges18 bronze badges

1 Comment

packetie Over a year ago

Thx @iboss for the tip and link. Turned out the main problem is the version mismatch on router.

JW Geertsma · Accepted Answer · 2021-09-13 06:44:21Z

3

The main issue is that you have used more than one export default keyword.

You could use:

 export default App
 export {home}
 etc etc

edited Sep 13, 2021 at 6:44

JW Geertsma

8753 gold badges18 silver badges22 bronze badges

answered Sep 13, 2021 at 6:40

Deepak Thakare

312 bronze badges

Comments

Taufan Arif · Accepted Answer · 2024-01-30 06:34:11Z

if you want to use export default then it should be in separated files because export default can only be used once for one file, here is the example App.jsx file:

import React from 'react';
import { Link } from 'react-router'

class App extends React.Component {
  render() {
     return (
        <div>
           <ul>
              <li><Link to = "/home">Home</Link></li>
              <li><Link to = "/about">About</Link></li>
              <li><Link to = "/contact">Contact</Link></li>
           </ul>

          {this.props.children}
        </div>
     )
  }
}

export default App;

do this for the rest of the files, Home.jsx, About.jsx, Contact.jsx with the same pattern.

but if you want it inside one file you can use export instead like this:

import React from 'react';
import { Link } from 'react-router'

export class App extends React.Component {
   render() {
      return (
         <div>
            <ul>
               <li><Link to = "/home">Home</Link></li>
               <li><Link to = "/about">About</Link></li>
               <li><Link to = "/contact">Contact</Link></li>
            </ul>

           {this.props.children}
         </div>
      )
   }
}

export class Home extends React.Component {
   render() {
      return (
         <div>
            <h1>Home...</h1>
         </div>
      )
   }
}

export class About extends React.Component {
   render() {
      return (
         <div>
            <h1>About...</h1>
         </div>
      )
   }
}

export class Contact extends React.Component {
   render() {
      return (
         <div>
            <h1>Contact...</h1>
         </div>
      )
   }
}

Mohamed Seif · Accepted Answer · 2025-04-30 18:29:49Z

0

in the App.jsx:

export default App;
export {Home, About, Contact};

then in the main.js:

import App, {Home, About, Contact} from "./App";

note that when you use any of the non-default functions you must use it with its same spelling and liter case as in the export statement and also you must use it as a function like this:

Home()
About()
Contact()

answered Apr 30 at 18:29

Mohamed Seif

1

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