How to use Existing typescript namespaced classes as external modules for nodejs

Question

The simple question here is how do I use namespaced typescript classes as external modules for use in node. The answer to that seems to be

It can't be done, don't try it, don't use namespaces

Well I am in the position that we have a large codebase that is all written in namespaces and we are now trying to use this code in node.js as well.

I am trying to figure out how to use our existing code.

I have got as far as compiling my namespaced code into a commonjs nodelibs folder that produces one js file and one d.ts for each ts file.

I have to add the following to each of my ts files that I want to be available to node:

namespace Organisation.Project.Entities{
    export class SomeThing{

    }
}

var module: {copy module definition from node.d.ts}

if(module)
{
    module.exports = Organisation.Project.Entities;
}

I can use this code in my node application:

var entities = require("../nodelibs/entities/entities");

var myThing = new entities.SomeClass();

despite there being both a entities.js and entities.d.ts at ../nodelibs/entities/entities there is no type info or compile time checking that SomeClass is a thing.

I can manually import the references file and manually type the instance of the class but in my case SomeClass is a class with a lot of statics on it so I can't fingure out how to type it properly...

var entities = require("../nodelibs/entities/entities");

var classRef = entities.SomeClass;

var myVar = classRef.staticProperty;

In this example I can't type classRef as SomeClass as it isn't an instance of SomeClass, it's the class constructor. How do I type classRef so that I can get access to the static properties on the class Some Class?

Thanks

Import gives various errors along the lines of cannot find module or entities.js is not a valid module... — Roaders
– Roaders, Commented Aug 31, 2016 at 15:17
In the imported file entities.ts, you should use the standard static ES6 syntax: export namespace Organisation.Project.Entities { /* ... */ }. After that, the compiler will be able to see it as a valid module. — Paleo
– Paleo, Commented Aug 31, 2016 at 15:20

Paleo · Accepted Answer · 2016-09-01 07:51:49Z

1

Write the code with ES6 modules

In the module, use the static ES6 module syntax:

// File entities.ts
export namespace Organisation.Project.Entities {
    export class SomeClass {
        public static abc = 'abc';
    }
}

Then, import your namespace:

// File main.ts
import {Organisation} from './entities';
type classRef = Organisation.Project.Entities.SomeClass;
var myVar = classRef.abc;

Compile for Node.js

Say the compiler to generate modules in the CommonJS format:

// File tsconfig.json
{
    "compilerOptions": {
        "module": "commonjs"
    },
    "exclude": [
        "node_modules"
    ]
}

Compile for the browser

In a browser, you can use a bundler or a loader. There is some configuration to do.

Bundlers:

Webpack (a tutorial here);
Browserify.

Loaders:

SystemJS (a tutorial here);
RequireJS.

edited Sep 1, 2016 at 7:51

answered Aug 31, 2016 at 15:27

Paleo

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2 Comments

Roaders Over a year ago

So close! I thought that was going to fix it but if I add export to the namespace then I can't compile without modules for use in the browser (with outFile specified). This is how we currently compile our codebase, all into one file. Thanks

Paleo Over a year ago

@Roaders : You can use a bundler (Webpack) or a loader (SystemJS) in order to work with a browser. I'll edit.

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How to use Existing typescript namespaced classes as external modules for nodejs

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Write the code with ES6 modules

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Compile for the browser

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Write the code with ES6 modules

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