Skip to main content

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 Namespaces are an outdated way to organize TypeScript code.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' {}).

.eslintrc.cjs
module.exports = {
  "rules": {
    "@typescript-eslint/no-namespace": "error"
  }
};

Try this rule in the playground ↗

Examples​

Examples of code with the default options:

module foo {}
namespace foo {}

declare module foo {}
declare namespace foo {}
Open in Playground

Options​

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:

module foo {}
namespace foo {}
Open in Playground

Examples of code for the { "allowDeclarations": false } option:

module foo {}
namespace foo {}
declare module foo {}
declare namespace foo {}
Open in Playground

allowDefinitionFiles​

Examples of code for the { "allowDefinitionFiles": true } option:

// 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 Playground

When 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.

Further Reading​

Resources​