eject-enum

Eject enums from your TypeScript codebase.

What is this?

eject-enum is a code rewriting tool for TypeScript codebases that
rewrites each TypeScript enum in your codebase to
the safer alternative.

Before rewriting:

``ts
/**
* Signals of traffic light.
*/
export enum TrafficLight {
/* Stop. /
Red,
/* Stop unless you can't do so safely. /
Yellow,
/* Go. /
Green,
}
`

After rewriting:

`ts
/**
* Signals of traffic light.
*/
export const TrafficLight = {
/* Stop. /
Red: 0,
/* Stop unless you can't do so safely. /
Yellow: 1,
/* Go. /
Green: 2,
} as const;

export type TrafficLight = (typeof TrafficLight)[keyof typeof TrafficLight];
`

Usage

> [!Note]
>
> **It is recommended to run code formatting tools after rewriting by
> eject-enum**, as it doesn't consider any code formatting configurations of
> your project when rewriting.

$3

You can execute eject-enum as a CLI tool:

`bash


npm

npx eject-enum [options...]

pnpm

pnpx eject-enum [options...]

Bun

bunx eject-enum [options...]

Deno >=2.6 (cf. https://deno.com/blog/v2.6#run-package-binaries-with-dx)

dx eject-enum [options...]
`

CLI Options:

`bash


If no targets are specified, it tries to use tsconfig.json

in the current directory as the default target.

npx eject-enum

Rewrite all files in projects specified by tsconfigs.

npx eject-enum path/to/tsconfig.json path/to/tsconfig2.json

Rewrite all Typescript files under the src and test directories,




except files under the src/foo directory.


npx eject-enum "src//.ts" "test//.ts" --exclude "src/foo/*/.ts"
`

$3

You can use eject-enum as a library from your scripts as well.

`bash
npm install --save-dev eject-enum
`

`ts
import { ejectEnum, EjectEnumTarget } from "eject-enum";

// Rewrite all files in projects specified by paths to tsconfigs.
ejectEnum(
EjectEnumTarget.projects([
"path/to/tsconfig.json",
"path/to/tsconfig2.json",
]),
);

// Rewrite all Typescript files under the src and test directories
// except files under the src/foo directory.
ejectEnum(
EjectEnumTarget.srcPaths({
include: ["src//.ts", "test//.ts"],
exclude: ["src/foo/*/.ts"],
}),
);
`

Features

- [x] Rewrite enums in the top-level as well as nested in functions, namespaces
and body of control flows (if, while, switch`).
- [x] Rewrite enums that have
constant enum expressions
as member's value.
- [x] Preserve comments as much as possible.
- [x] Preserve original expressions of enum members in the original code as
comments.
- [x] Rewrite
an enum member used as a type.

Limitations

eject-enum have some limitations about code rewriting. They originate from
limitations of the TS Compiler API/ts-morph.

- Can't rewrite enums that have computed enum members.
- e.g. referring variables, members of other enums (even constant members)
- Can't preserve original trailing comments of enum members.