Registry / devops / babel-plugin-const-enum

babel-plugin-const-enum

library1.2.0jsnpmunverified

babel-plugin-const-enum is a Babel plugin designed to transform TypeScript `const enum` declarations. Babel's standard TypeScript presets/plugins (`@babel/preset-typescript` or `@babel/plugin-transform-typescript`) do not inherently handle `const enum`s, which are erased during TypeScript's compilation if not explicitly preserved or transformed. This plugin, currently at version 1.2.0, provides a solution by enabling two transformation strategies: `removeConst` (the default, converting `const enum`s into regular `enum`s) or `constObject` (transforming them into constant object literals). The `constObject` strategy is particularly useful for environments where minifiers like Terser or UglifyJS can then effectively inline these values, leading to smaller bundle sizes. It acts as a critical intermediary step for projects using TypeScript with Babel that rely on `const enum`s, ensuring their correct processing and optimization. The release cadence is driven by community needs and Babel ecosystem changes.

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npm install babel-plugin-const-enum

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INSTALL

IMPORT

SIG · BABEL-PLUGIN-CONST

babel-plugin-const-enum

devopsjavascriptv1.2.0

Install

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Import

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Disk

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Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

const-enum

✓ { "plugins": ["const-enum"] }

✗ { "plugins": ["@babel/plugin-transform-typescript", "const-enum"] }

Referenced as a string in Babel config. It must be listed before `@babel/plugin-transform-typescript` if using plugins directly.

const-enum with options

✓ { "plugins": [["const-enum", {"transform": "constObject"}]] }

✗ { "plugins": ["const-enum": {"transform": "constObject"}] }

When passing options, the plugin entry must be an array where the first element is the plugin name and the second is an object of options.

babel-plugin-const-enum (require)

✓ require('babel-plugin-const-enum')

✗ import constEnumPlugin from 'babel-plugin-const-enum'

If configuring Babel dynamically in `babel.config.js`, plugins are typically `require`d, not `import`ed directly as a module for application code.

Configures Babel to use `babel-plugin-const-enum` with `@babel/preset-typescript`, transforming `const enum`s into constant object literals for better minification.

{ "presets": [ [ "@babel/preset-typescript", { "is TSX": true, // Example option for preset-typescript "allExtensions": true } ] ], "plugins": [ // Must run BEFORE @babel/preset-typescript if plugin-transform-typescript is implicitly used. // Or explicitly before @babel/plugin-transform-typescript if listed directly. ["const-enum", {"transform": "constObject"}] ] }

Debug

Known issues

breakingIncorrect plugin order will cause `const enum`s to not be transformed correctly or result in syntax errors.

fix

Ensure `babel-plugin-const-enum` is listed BEFORE `@babel/plugin-transform-typescript` in your Babel configuration's plugin array. If using `@babel/preset-typescript`, no explicit ordering is usually needed as plugins run before presets.

affects: >=1.0.0

gotchaRunning `babel-plugin-const-enum` on non-TypeScript source files (e.g., Flow-typed JavaScript in `node_modules` in React Native projects) can lead to `SyntaxError`s.

fix

Use `babel-preset-const-enum` to apply the plugin only to TypeScript files, or manually configure your Babel loader/plugin to exclude non-TypeScript files (e.g., `exclude: /node_modules/(?!my-typescript-lib)/`).

affects: >=1.0.0

gotchaThe default `transform: removeConst` option converts `const enum`s to regular `enum`s, which may not be fully optimized by minifiers. The `transform: constObject` option provides better minification but changes the runtime shape.

fix

If minification and bundle size are critical, configure the plugin with `["const-enum", {"transform": "constObject"}]` to convert enums into constant object literals that optimizers can inline.

affects: >=1.0.0

Errors

Common errors & fixes

SyntaxError: Unexpected token, expected "("

The `babel-plugin-const-enum` is being applied to non-TypeScript files that might contain different syntax, such as Flow annotations.

fix

Ensure the plugin only runs on TypeScript files. Use `babel-preset-const-enum` or configure your Babel setup to explicitly include/exclude files based on their type (e.g., `test: /\.tsx?$/` for Webpack Babel loader).

ReferenceError: MyEnum is not defined

`const enum` was stripped by Babel without transformation, likely due to incorrect plugin order.

fix

Verify that `babel-plugin-const-enum` is listed before `@babel/plugin-transform-typescript` in your Babel configuration. If using `@babel/preset-typescript`, ensure `babel-plugin-const-enum` is listed in the `plugins` array (plugins always run before presets).

Upgrade

Version history

1.2.0latest on npm

Audit

Dependencies

@babel/corerequiredBabel plugins require Babel's core runtime.

Agent activity

4 hits · last 30 days

node

Resources

githubhttps://github.com/dosentmatter/babel-plugin-const-enum ↗

packagehttps://www.npmjs.com/package/babel-plugin-const-enum ↗