Convert Namespaced Javascript Functions to Typescript

Question

I know that all javascript is valid typescript but I'd like to start converting my javascript to typescript conventions. I'm battling this one snippet of JS:

My standard Javascript that works

if (MyCompany === undefined) {
    var MyCompany = {};
}
MyCompany.Uploader = MyCompany.Uploader || {};
MyCompany.Uploader.Core = function (config) {
    'use strict';
    function build() {
        console.log("building");
    }
    return {
        build: build
    };
};
var config = {this: "that};
MyCompany.Uploader.Core(config).build(); // outputs building to console

I've been messing with multiple approaches and I feel like I not close enough.

My failed attempt at converting to Typescript

namespace MyCompany.Uploader {
    export var Core = (config:any) => {
        function build() {
            console.log("building");
        }
    };
}
let configobj = {here:"there"};
MyCompany.Uploader.Core(configobj).build();

This simply doesn't work. I can't seem to access the build function. I'm sure this is a rookie mistake.

The error I get: Property build does not exist on type void

Answer 1

That's because you did not add an important part of your javascript code into the typescript version, and that's the return object which contains the reference for the build function, it should be:

namespace MyCompany.Uploader {
    export var Core = (config: any) {
        function build() {
            console.log("building");
        }

        return {
            build: build
        }
    };
}

let configobj = { here: "there" };
MyCompany.Uploader.Core(configobj).build();

You can also define interfaces for the config and the return object:

namespace MyCompany.Uploader {
    export interface Config {
        here: string;
    }

    export interface Builder {
        build: () => void;
    }

    export var Core = (config: Config): Builder => {
        function build() {
            console.log(config.here);
        }

        return {
            build: build
        }
    };
}

let configobj = { here: "there" };
MyCompany.Uploader.Core(configobj).build();