rollup-plugin-const-enum

A Rollup plugin that uses the TypeScript compiler API to inline enum member accesses such as Colors.Red -> 0 or Status.Active -> "active".

2.0.0 is a major refactor that replaces the original regex-based scanning approach with a more robust TypeScript compiler API-based implementation. This allows for more accurate and reliable enum member inlining, especially in complex codebases with various import patterns and TypeScript features.

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ChangeLog

Install

Use pnpm to install as a devDependency:

pnpm add -D rollup-plugin-const-enum rollup typescript

Quick usage

Place the plugin before your TypeScript transpilation step so it can still see the original enum syntax:

import { constEnum } from 'rollup-plugin-const-enum';

export default {
  // ...
  plugins: [
    constEnum(), // place it near the front
    ...
  ],
};

Behavior

• Only enum member accesses that are available in the current file are considered.
• Cross-file enums must be explicitly imported in the current module before they can be inlined.
• Same-file enum declarations can always be inlined.
• The transform returns a sourcemap.

Options

The plugin accepts an optional options object. All options are optional and have sensible defaults.

• inlineNonConstEnums: boolean — Inline regular enum members in addition to const enum. Default: false.
• inlineNames?: Array<string | RegExp> — Restrict inlining to enums whose declaration names match one of these rules. Default: undefined.

Validation:

• inlineNonConstEnums must be a boolean when provided.
• inlineNames must be an array of string | RegExp when provided.

Example

import constEnum from 'rollup-plugin-const-enum';

export default {
  plugins: [
    constEnum({
      inlineNonConstEnums: true,
      inlineNames: ['Color', /^Status$/],
    }),
  ],
};

Important notes

• It relies on TypeScript's symbol resolution, so project tsconfig.json settings can affect module resolution.
• If TypeScript cannot evaluate an enum member access as a constant, the original code is kept unchanged.
• The plugin only transforms TypeScript source files.

License

MIT