How to use namespaces with import in TypeScript?

To use namespaces with import in TypeScript, we can create ES6 modules and import them.

For instance, we write

UtilBase.ts

import * as path from "path";

export default class UtilBase {
  protected fixPath(value: string): string {
    return value.replace("/", path.sep);
  }
}

to export the UtilBase class as a default export.

Then we can import the module as a default import with

import UtilBase from "./UtilBase";
export default class UtilOne extends UtilBase {
  //...
}