Rule Definition
While namespaces sometime have their uses, they add an extra level of indirection when combined with modules. This can quickly become confusing for users, and is usually unnecessary. The general idea of namespacing is to provide logical grouping of constructs and to prevent name collisions. However since the module file is in itself a logical grouping, and its top-level name is defined by the code that imports it, it is unnecessary to use an additional module layer for exported objects.

Remediation
Favor using modules over namespaces for structuring you code.

Violation Code Sample

//in shapes.ts module
export namespace Shapes {
    export class Triangle { /* ... */ }
    export class Square { /* ... */ }
}


//in shapeConsumer.ts module
import * as shapes from "./shapes";
let t = new shapes.Shapes.Triangle(); // shapes.Shapes?

Fixed Code Sample

// in shapes.ts module
export class Triangle { /* ... */ }
export class Square { /* ... */ }


// in shapeConsumer.ts module
import * as shapes from "./shapes";
let t = new shapes.Triangle();

https://www.typescriptlang.org/docs/handbook/namespaces-and-modules.html https://www.typescriptlang.org/docs/handbook/modules.html