Named export
In TS you can export with the export keyword. It then can be imported via import {name} from "./mydir";. This is called a named export. A file can export multiple named exports. Also the names of the imports have to match the exports. For example:
// foo.js file
export class foo{}
export class bar{}
// main.js file in same dir
import {foo, bar} from "./foo";
The following alternative syntax is also valid:
// foo.js file
function foo() {};
function bar() {};
export {foo, bar};
// main.js file in same dir
import {foo, bar} from './foo'
Default export
We can also use a default export. There can only be one default export per file. When importing a default export we omit the square brackets in the import statement. We can also choose our own name for our import.
// foo.js file
export default class foo{}
// main.js file in same directory
import abc from "./foo";
It's just JavaScript
Modules and their associated keyword like import, export, and export default are JavaScript constructs, not typescript. However typescript added the exporting and importing of interfaces and type aliases to it.