Un used variable is emmitted while transpiling enums.

[madhurakhal]

TypeScript code

module Workspace {
  export enum State {
    IN_PROGRESS,
    BUFFER_RENDERED,
    SKIPPED,
    TIME_OUT
  }
}

Compled JavaScript Code.

 
var Workspace;
(function (Workspace) {
    (function (State) {
        State[State["IN_PROGRESS"] = 0] = "IN_PROGRESS";
        State[State["BUFFER_RENDERED"] = 1] = "BUFFER_RENDERED";
        State[State["SKIPPED"] = 2] = "SKIPPED";
        State[State["TIME_OUT"] = 3] = "TIME_OUT";
    })(Workspace.State || (Workspace.State = {}));
    var State = Workspace.State; // this code is use no where.
})(Workspace || (Workspace = {}));

I am using TypeScript version 1.5.3

[xLama]

It´s nccessary to use State enum. Consider this example:

TS

module Workspace {
  export enum State {
    IN_PROGRESS,
    BUFFER_RENDERED,
    SKIPPED,
    TIME_OUT
  }

  class A{
      buffer:State = State.BUFFER_RENDERED;
  }

} 

JAVASCRIPT

var Workspace;
(function (Workspace) {
    (function (State) {
        State[State["IN_PROGRESS"] = 0] = "IN_PROGRESS";
        State[State["BUFFER_RENDERED"] = 1] = "BUFFER_RENDERED";
        State[State["SKIPPED"] = 2] = "SKIPPED";
        State[State["TIME_OUT"] = 3] = "TIME_OUT";
    })(Workspace.State || (Workspace.State = {}));
    var State = Workspace.State;
    var A = (function () {
        function A() {
            this.buffer = State.BUFFER_RENDERED;
        }
        return A;
    })();
})(Workspace || (Workspace = {}));

But I don´t understand this:

module Workspace {
   export enum State {
    IN_PROGRESS,
    BUFFER_RENDERED,
    SKIPPED,
    TIME_OUT
  }
} 


var Workspace;
(function (Workspace) {
    (function (State) {
        State[State["IN_PROGRESS"] = 0] = "IN_PROGRESS";
        State[State["BUFFER_RENDERED"] = 1] = "BUFFER_RENDERED";
        State[State["SKIPPED"] = 2] = "SKIPPED";
        State[State["TIME_OUT"] = 3] = "TIME_OUT";
    })(Workspace.State || (Workspace.State = {}));
    var State = Workspace.State;
})(Workspace || (Workspace = {}));

JS could be:

var Workspace;
(function (Workspace) {
    var State;
    (function (State) {
        State[State["IN_PROGRESS"] = 0] = "IN_PROGRESS";
        State[State["BUFFER_RENDERED"] = 1] = "BUFFER_RENDERED";
        State[State["SKIPPED"] = 2] = "SKIPPED";
        State[State["TIME_OUT"] = 3] = "TIME_OUT";
    })(State || (State = {}));
    Workspace.State = State;
})(Workspace || (Workspace = {}));

Instead of :

var Workspace;
(function (Workspace) {
    (function (State) {
        State[State["IN_PROGRESS"] = 0] = "IN_PROGRESS";
        State[State["BUFFER_RENDERED"] = 1] = "BUFFER_RENDERED";
        State[State["SKIPPED"] = 2] = "SKIPPED";
        State[State["TIME_OUT"] = 3] = "TIME_OUT";
    })(Workspace.State || (Workspace.State = {}));
    var State = Workspace.State;
})(Workspace || (Workspace = {}));

[madhurakhal]

Yep your code looks perfectly fine and reasonable when using the State enum at the same file. But In my case I am using State enum in different files. which means the only enum related code is there. So

var State = Workspace.State;

is unused one and also I am using Visual Studio Code which also complain the same.

Use case seniorio in another file after importing the enum (I am using backbone model)

this.model.set('state', Workspace.State.BUFFER_RENDERED);

In my point of view.

var State = Workspace.State;

should be there iff the State enum is used in same file.

Thanks

[DanielRosenwasser]

@madhurakhal I don't think removing unused declarations is something we're aiming to achieve - a namespace is certainly consumable by others if any other code occurs after this. This is an optimization that linters and/or optimizers could work on.

---

@xLama

JS could be

var Workspace;
(function (Workspace) {
    var State;
    (function (State) {
        State[State["IN_PROGRESS"] = 0] = "IN_PROGRESS";
        State[State["BUFFER_RENDERED"] = 1] = "BUFFER_RENDERED";
        State[State["SKIPPED"] = 2] = "SKIPPED";
        State[State["TIME_OUT"] = 3] = "TIME_OUT";
    })(State || (State = {}));
    Workspace.State = State;
})(Workspace || (Workspace = {}));

The idea point is that enums merge with prior declarations (hence the Workspace.State || (Workspace.State = {}).) In your example, you create a variable that is always going to start out undefined (State), then initialize it, and then overwrite Worspace.State which isn't the desired behavior.

namespace E {
    export const C = 20;
}

enum E {
    A = 10,
    B = 20,
}

[RyanCavanaugh]

@rbuckton is this fixed in the transforms branch?

[RyanCavanaugh]

Accepting PRs for the transforms branch / 2.1 to make the emit the same as the namespace emit code (declare a var above the IIFE, then assign to the var in the IIFE arguments)