Suggestion: flip the assignment direction of generated enums to save some bits

Search Terms

enum assignment

Suggestion

Flip the assignment order

Use Cases

enums

Examples

enum Action {
  foo
  bar
  baz
  thequickbrownfoxjumpsoverthelazydog
}

currently generates:

"use strict";
var Action;
(function (Action) {
    Action[Action["foo"] = 0] = "foo";
    Action[Action["bar"] = 1] = "bar";
    Action[Action["baz"] = 2] = "baz";
    Action[Action["thequickbrownfoxjumpsoverthelazydog"] = 3] = "thequickbrownfoxjumpsoverthelazydog";
})(Action || (Action = {}));

Suggesting instead:

"use strict";
var Action;
(function (Action) {
    Action[Action[0] = "foo"] = 0;
    Action[Action[1] = "bar"] = 1;
    Action[Action[2] = "baz"] = 2;
    Action[Action[3] = "thequickbrownfoxjumpsoverthelazydog"] = 3;
})(Action || (Action = {}));

Checklist

My suggestion meets these guidelines:

• This wouldn’t be a breaking change in existing TypeScript/JavaScript code
• This wouldn’t change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn’t a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
• This feature would agree with the rest of TypeScript’s Design Goals.

[dsherret]

@MarkKahn depends on how creative people get 😃

let count = 0;
enum MyEnum {
    A = fn(),
    B = (() => {
        Object.defineProperty(MyEnum, "A", {
            get() {
                count++;
                return count;
            }
        })
        return 5;
    })(),
    C = A,
    D = A
}

Yeah, ok… nobody would do this, but you never know.

[polkovnikov-ph]

let c = 0;
const f = () => c++;
enum A {
    B = f(),
    C = f(),
}

Flipping assignment order leads to incorrect behavior.

Duplicate of #29838 and #19848