Duplicate identifier error when naming a class 'Node'

[pb82]

TypeScript Version: 2.3.3
Node.js Version: 7.10.0

Code

class Node {}

Safe the file as index.ts and run tsc index.ts. No tsconfig.json.

Expected behavior:
Compiles without error.

Actual behavior:
Compiler returns the following error:

../../../usr/lib/node_modules/typescript/lib/lib.d.ts(12520,11): error TS2300: Duplicate identifier 'Node'.
../../../usr/lib/node_modules/typescript/lib/lib.d.ts(12572,13): error TS2300: Duplicate identifier 'Node'.
index.ts(1,7): error TS2300: Duplicate identifier 'Node'.

Renaming the class makes it pass.

[kitsonk]

Because Node is already part of the global namespace and cannot be redeclared. It needs to be part of a module, so it is not part of the global namespace.

[pb82]

That makes sense, thanks. Closing it now.

[brandonbloom]

What do you mean by "It needs to be part of a module"? I ran in to this exactly name collision, but I've got my class definition in a .ts file that is being loaded via import. My tsconfig.json has the module system set to "commonjs".

[kitsonk]

You would need to provide more details. What does your module look like? If it doesn't have any imports or exports then TypeScript won't treat it as a module.

This will error while this works:

-class Node {
+export class Node {

}

[brandonbloom]

If it doesn't have any imports or exports then TypeScript won't treat it as a module.

Whoa. I did not realize that.

This particular module will have no imports and did not yet have any exports, since I had just started writing it. I wasn't planning to export the Node type, but was going to export some functions that used it.

Thank you!

[kitsonk]

As just discussed in #18232, if you need have something that you want to be considered a module without any imports or exports you can simply use:

export { }

Which will end up being stripped when the module is emitted.