no-namespace
Disallow TypeScript namespaces.
Extending "plugin:@typescript-eslint/recommended"
in an ESLint configuration enables this rule.
TypeScript historically allowed a form of code organization called "custom modules" (module Example {}
), later renamed to "namespaces" (namespace Example
).
Namespaces are an outdated way to organize TypeScript code.
ES2015 module syntax is now preferred (import
/export
).
This rule does not report on the use of TypeScript module declarations to describe external APIs (
declare module 'foo' {}
).
module.exports = {
"rules": {
"@typescript-eslint/no-namespace": "error"
}
};
Try this rule in the playground ↗
Examples
Examples of code with the default options:
- ❌ Incorrect
- ✅ Correct
module foo {}
namespace foo {}
declare module foo {}
declare namespace foo {}
Open in Playgrounddeclare module 'foo' {}
// anything inside a d.ts file
Open in PlaygroundOptions
This rule accepts the following options:
type Options = [
{
/** Whether to allow `declare` with custom TypeScript namespaces. */
allowDeclarations?: boolean;
/** Whether to allow `declare` with custom TypeScript namespaces inside definition files. */
allowDefinitionFiles?: boolean;
},
];
const defaultOptions: Options = [
{ allowDeclarations: false, allowDefinitionFiles: true },
];
allowDeclarations
Examples of code with the { "allowDeclarations": true }
option:
- ❌ Incorrect
- ✅ Correct
module foo {}
namespace foo {}
Open in Playgrounddeclare module 'foo' {}
declare module foo {}
declare namespace foo {}
declare global {
namespace foo {}
}
declare module foo {
namespace foo {}
}
Open in PlaygroundExamples of code for the { "allowDeclarations": false }
option:
- ❌ Incorrect
- ✅ Correct
module foo {}
namespace foo {}
declare module foo {}
declare namespace foo {}
Open in Playgrounddeclare module 'foo' {}
Open in PlaygroundallowDefinitionFiles
Examples of code for the { "allowDefinitionFiles": true }
option:
- ❌ Incorrect
- ✅ Correct
// if outside a d.ts file
module foo {}
namespace foo {}
// if outside a d.ts file and allowDeclarations = false
module foo {}
namespace foo {}
declare module foo {}
declare namespace foo {}
Open in Playgrounddeclare module 'foo' {}
// anything inside a d.ts file
Open in PlaygroundWhen Not To Use It
If your project was architected before modern modules and namespaces, it may be difficult to migrate off of namespaces. In that case you may not be able to use this rule for parts of your project. You might consider using ESLint disable comments for those specific situations instead of completely disabling this rule.