Microsoft/TypeScript

External modules with AMD always requires "exports" even when it is not used

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#669 opened on Sep 12, 2014

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 (6 comments) (2 reactions) (0 assignees)TypeScript (48,455 stars) (6,726 forks)batch import
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Description

Here's a small external module that explicitly exports a module:

module Foo {
    export var foo = 42;
}
export = Foo;

The code generated for this is:

define(["require", "exports"], function(require, exports) {
    var Foo;
    (function (Foo) {
        Foo.foo = 42;
    })(Foo || (Foo = {}));

    return Foo;
});

This feels like bad AMD since you are requiring the "exports" magic dependency, but then not using it and instead returning Foo directly.

It's annoying for minimal AMD loaders since they can't assume the object return of your module is your "exports" object and have to guess that you really meant to return something that overrode the "exports" object you asked for.

Furthermore, why bother declaring a dependency on 'require' when it's not used?

Contributor guide

Tech stack
typescript
Domain
tooling
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Understanding of TypeScript compiler internalsFamiliarity with AMD module format
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
Investigate the TypeScript compiler's emitter code in src/compiler/emitter.ts, specifically the functions that output AMD module dependencies. The issue is that 'exports' and 'require' are always included even when not used. Look for where the list of dependencies is built and add logic to exclude those that are not referenced in the module body. Review comments and associated issues for any prior attempts or considerations. Ensure the fix only affects AMD output and preserves correct behavior for other module systems.