Why es6 react component works only with “export de

问题:

This component does work:

export class Template extends React.Component {
    render() {
        return (
            <div> component </div>
        );
    }
};
export default Template;

If i remove last row, it doesn't work.

Uncaught TypeError: Cannot read property 'toUpperCase' of undefined

I guess, I don't understand something in es6 syntax. Isn't it have to export without sign "default"?

回答1:

Exporting without default means it's a "named export". You can have multiple named exports in a single file. So if you do this,

class Template {}
class AnotherTemplate {}

export { Template, AnotherTemplate }

then you have to import these exports using their exact names. So to use these components in another file you'd have to do,

import {Template, AnotherTemplate} from './components/templates'

Alternatively if you export as the default export like this,

export default class Template {}

Then in another file you import the default export without using the {}, like this,

import Template from './components/templates'

There can only be one default export per file. In React it's a convention to export one component from a file, and to export it is as the default export.

You're free to rename the default export as you import it,

import TheTemplate from './components/templates'

And you can import default and named exports at the same time,

import Template,{AnotherTemplate} from './components/templates'