Extend a CoffeeScript class loaded with RequireJS inside a TypeScript code

Question

Currently I have a large codebase developed with CoffeeScript and want to extend it with some TypeScript.

Let's say I have the following code in the CoffeeClass.coffee file:

define 'CoffeeClass', ->
  class CoffeeClass
    foo: () -> 1

It is meant to be loaded through require in the following manner (let's call this file CoffeeUser.coffee):

require ['CoffeeClass'], (CoffeeClass) ->
  class MyClass extends CoffeeClass
    foo: () -> super() + 1
  console.log (new MyClass().foo()) # => 2

Now it can be loaded in browser with the standard RequireJS markup:

<script data-main="CoffeeUser.js" src="require.js"></script>

I want to extend the CoffeeClass from the TypeScript code. That's what I've tried:

First write a CoffeeClass.d.ts definiton file (I know it is wrong but it's showing what I'm trying to achieve):

export class CoffeeClass {
  foo(): number;
}

And then try to use it from TypeScriptUser.ts:

import CoffeeClass = require('CoffeeClass');
class TypeScriptUser extends CoffeeClass {
  foo(): number {
    return super.foo() + 1;
  }
}

But it won't compile partly because I cannot find the right syntax for the d.ts file and partly because I cannot properly tell the compiler how to extend the CoffeeClass (as far as I can tell the compiler cannot understand that CoffeeClass is really a class and not just a module).

So can I tell the TypeScript compiler that the module is a class here? If no, how would you recommend me to change the CoffeeClass design to extend it from TypeScript code and don't lose all the type safety?

ForNeVeR · Accepted Answer · 2014-10-04 18:03:33Z

2

Finally I've found the solution. That's the special export = syntax. Here it is. CoffeeClass.d.ts:

declare class CoffeeClass {
    foo(): number;
}

export = CoffeeClass;

And TypeUser.ts:

/// <reference path="CoffeeClass.d.ts" />
import CoffeeClass = require('CoffeeClass')
class MyClass extends CoffeeClass {
    foo() {
        return super.foo() + 1;
    }
}

console.log(new MyClass().foo()); // => 2

Note that the compiler will infer the proper require call when compiling the code.

edited Oct 4, 2014 at 18:03

answered Oct 4, 2014 at 16:46

ForNeVeR

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