CODEWITHSUNDEEP
javascriptnode.jstypescripttsc
Grofit
Grofit

Reputation: 18445

Duplicate identifier error with d.ts file and nodejs require with same name

Now I am sure the issue is because there is a d.ts file included which contains a module called "Shared", and a require statement which includes a variable of the same name if it is being used in a NodeJS environment.

// shared.d.ts
declare module Shared { ... }

// other_module.ts
/// <reference path="shared.d.ts"/>
if(require) { var Shared = require("shared"); }
export class Something {
    public someVar = new Shared.SomethingElse("blah");
}

So when I compile other_module.ts (which is actually a lot of separate files), it tells me Shared is a duplicate identifier, which I can understand as TS thinks Shared is a module, but then is being told it is the return of require.

The problem here is that the output of modules need to be compatible with nodeJS's require system, so in this case when other_module is required it will be in its own scope and will not know about Shared.SomethingElse so the require is needed so the internal modules in other_module will be able to access the Shared library, but in the browser environment it would get Shared.SomethingElse via the global scope.

If I remove the reference then the file wont compile as it doesn't know about Shared, if I remove the require when the module is loaded into nodejs (var otherModule = require("other_module")) it will complain that it doesn't know about Shared. So is there a way to solve this?

Upvotes: 2

Views: 5699

Answers (1)

basarat
basarat

Reputation: 275799

First the error

Duplicate identifier because you have Shared in shared.d.ts + in other_module.ts.

FIX A, be all external

If you want to use amd / commonjs ie. external modules, you need to use import/require (not var/require like you are doing). Using an import creates a new variable declaration space and therefore you are no longer polluting the global namespace Shared from other_module.ts. In short : 

// shared.d.ts
declare module Shared { 
   export function SomethingElse(arg:string):any;
}
declare module 'shared'{ 
    export = Shared; 
}

And a typesafe import:

// other_module.ts

/// <reference path="shared.d.ts"/>
import Shared = require("shared"); 

export class Something {
    public someVar = new Shared.SomethingElse("blah");
}

FIX B, as you were, but you need to use a different name then

Inside other_module don't use the name Shared locally if local scope is global scope. I recommend you just use external everywhere and compile for node with commonjs and browser with amd as shown in fix A, but if you must here is a compile fixed other_module.ts. 

// other_module.ts
/// <reference path="shared.d.ts"/>
var fooShared: typeof Shared;
if(require) {  fooShared = require("shared"); }
else { fooShared = Shared; } 
export class Something {
    public someVar = new fooShared.SomethingElse("blah");
}

Upvotes: 6

Related Questions