rollup-utils

0.0.5 verified Mon Apr 27 auth: no javascript

A set of utility functions for Rollup plugins, forked from @rollup/pluginutils but using path-browserify instead of the Node.js path module to support browser environments. Version 0.0.5 (released on npm, but no release cadence noted). Requires Node >=14.0.0 and Rollup ^1.20.0||^2.0.0||^3.0.0||^4.0.0. Ships TypeScript type definitions. Key differentiators from @rollup/pluginutils: browser compatibility via path-browserify dependency. Includes addExtension, attachScopes, createFilter, dataToEsm, extractAssignedNames, makeLegalIdentifier, and normalizePath functions.

Common errors

error Error [ERR_REQUIRE_ESM]: require() of ES Module /path/to/rollup-utils/dist/index.js from /path/to/index.js not supported. ↓

cause Using CommonJS require() on an ESM-only package.

fix

Switch to import syntax (e.g., import { createFilter } from 'rollup-utils').

error TypeError: (0 , _rollupUtils.createFilter) is not a function ↓

cause Incorrect import style, probably using default import when createFilter is named export.

fix

Use import { createFilter } from 'rollup-utils' instead of import createFilter from 'rollup-utils'.

error Cannot find module 'rollup' ↓

cause rollup is a peer dependency and not installed automatically.

fix

Ensure rollup is installed: npm install rollup --save-dev

Warnings

breaking Breaking change: package is ESM-only. CommonJS require() will throw an error. ↓

fix Use import syntax instead of require().

gotcha createFilter returns a function that expects a string or unknown id, not an object. Passing an object may silently return false. ↓

fix Ensure you pass a string ID (e.g., the module path).

gotcha addExtension does not add an extension if the filename already has an extension (including '.' only). ↓

fix Check filename before calling addExtension if you want to force extension addition.

gotcha attachScopes requires the AST to already have 'scope' property attached to nodes; it mutates the AST. ↓

fix Call attachScopes once on the AST, then walk and manage scope manually.

Install

npm install rollup-utils

yarn add rollup-utils

pnpm add rollup-utils

Imports

* as utils
wrong
```
const utils = require('rollup-utils');
```
correct
```
import * as utils from 'rollup-utils';
```
Package is ESM-only (ES module). CommonJS require() will cause an error.

addExtension

wrong

const addExtension = require('rollup-utils').addExtension;

correct

import { addExtension } from 'rollup-utils';

Named export, not default export. Use named import syntax.

createFilter
wrong
```
import createFilter from 'rollup-utils';
```
correct
```
import { createFilter } from 'rollup-utils';
```
createFilter is a named export, not default. Incorrect as default import.
attachScopes
wrong
```
import { attachScopes } from '@rollup/pluginutils';
```
correct
```
import { attachScopes } from 'rollup-utils';
```
attachScopes is from 'rollup-utils', not '@rollup/pluginutils' (though the API is similar).

dataToEsm

import { dataToEsm } from 'rollup-utils';

Named export; use exactly as shown.

Quickstart

Shows how to import createFilter and use it in a Rollup plugin's transform hook to include only specific module IDs.

import { createFilter } from 'rollup-utils';
import resolve from '@rollup/plugin-node-resolve';

export default {
  input: 'src/index.js',
  output: { dir: 'dist', format: 'es' },
  plugins: [
    resolve(),
    {
      name: 'my-plugin',
      transform(code, id) {
        const filter = createFilter('src/**/*.js', 'node_modules/**');
        if (!filter(id)) return null;
        // Transform only included modules
        return code.replace(/__VERSION__/g, '1.0.0');
      }
    }
  ]
};