Why so many angular4 project use export class xxx rather than export default class xxx?

Question

I know what's the difference between export class xxx and export default class xxx.

But I saw many angular4 project use export class xxx like this:

@Component({
  selector: 'call-record',
  templateUrl: './collection.component.html',
  styleUrls: ['./collection.component.css']
})
export class collection {

}

I think if there is one class or whatever to export, use export default xxx should be better?

So I can import it like this: import xxx from './somewhere'

not this: import {xxx} from './somewhere'.

There's also some issues around using `default` keyword when using with angular-cli, see https://github.com/angular/angular-cli/issues/3826 — penleychan, Jul 27 '17 at 13:48
Possible duplicate of [Typescript export vs. default export](https://stackoverflow.com/questions/33305954/typescript-export-vs-default-export) — LarsMonty, Jul 27 '17 at 16:17
@LarsMonty @Maximus I don't think my question is duplicated. As I said, I __know__ what's the difference between `export xxx` and `export default xxx`. My question's point is why so many projects of angular4 use `export xxx` not `export default xxx` — Lin Du, Jul 28 '17 at 06:07

score 0 · Accepted Answer · answered Sep 15 '20 at 10:57

There are some problems with maintainability:

If you refactor xxx in the somewhere module, it will not be renamed in the file that imports the module.
If you eventually need to export more useful information(not only concrete class but also types, interfaces, constants) from the file then you must use export { ConcreteClass, SomeType, ISomeInterface, SomeConstant}.
The discoverability of the default export is very poor, and you cannot intelligently distinguish whether a module has a default export
Editor/IDE automatic completion
If you use CommonJs like this const {default} = require('./somewhere'), you most likely want to rename the default export.
Prevent spelling errors. If you use import Foo from './foo' during development, you won't get any spelling errors. Others might write import foo from'./foo' like this.

For the above reasons, the default export should be avoided.

Why so many angular4 project use export class xxx rather than export default class xxx?

1 Answers1