passsy / prefer-union-over-enumr3

Prefer a union of literals over a TypeScript enum

Public

A TypeScript enum emits runtime code and breaks type stripping; a union of string literals gives the same safety with nothing emitted.

detector.tsisolate · reads files, writes none · no network · 100 ms · 32 MBEdit

import { onWrite } from "@wellactually/sdk/v3";

// Anchored at the start of the line, so an enum in a comment or a string is not one.
const ENUM = /^\s*(?:export\s+)?(?:declare\s+)?(?:const\s+)?enum\s+[A-Za-z_$]/;

// A declaration file describes someone else's enum. There is nothing to rewrite.
onWrite({
  globs: ["**/*.{ts,tsx,mts,cts}", "!**/*.d.{ts,mts,cts}"],
  *detect(event) {
    for (const written of event.written) {
      if (ENUM.test(written.text)) {
        yield { line: written.line };
      }
    }
  },
});

package.jsonEdit

{
  "name": "prefer-union-over-enum",
  "private": true,
  "tags": [
    "typescript",
    "enum"
  ]
}