rollup-plugin-less

1.1.3 verified Mon Apr 27 auth: no javascript maintenance

A Rollup plugin for compiling Less files to CSS. Current stable version is 1.1.3, released in 2020. It supports inserting CSS into the DOM or writing to a file. Minimal configuration, but limited flexibility compared to alternatives like rollup-plugin-postcss. Not actively maintained; last commit was in 2021.

Common errors

error Error: Cannot find module 'less' ↓

cause Less is not installed or not found in node_modules.

fix

npm install less --save-dev

error TypeError: Cannot read properties of undefined (reading 'render') ↓

cause Incorrect import; using require without .default in CommonJS.

fix

Use require('rollup-plugin-less').default or switch to ES import.

error Error: Plugin returned an object, but expected an object with code or map property ↓

cause Plugin version incompatibility with Rollup 2+; the plugin's transform hook returns undefined for non-Less files.

fix

Update to the latest version or ensure include/exclude patterns are correct.

Warnings

gotcha The plugin expects less to be installed as a peer dependency; if not present, it will throw a runtime error. ↓

fix Run npm install less --save-dev alongside the plugin.

gotcha When insert is true, CSS is injected into <head> only in browser environments; it will fail in Node.js SSR contexts. ↓

fix Use output option to write CSS to a file for SSR compatibility.

deprecated The option 'useDefault' is not supported; the plugin always uses the less default render. ↓

fix Remove any 'useDefault' option from plugin configuration.

Install

npm install rollup-plugin-less

yarn add rollup-plugin-less

pnpm add rollup-plugin-less

Imports

default (less)
wrong
```
const less = require('rollup-plugin-less')
```
correct
```
import less from 'rollup-plugin-less'
```
Package does not export a named function; default import only.
Options
```
import type { LessOptions } from 'rollup-plugin-less'
```
For TypeScript users, types are provided; use type import for options.

less function

wrong

const less = require('rollup-plugin-less')

correct

const less = require('rollup-plugin-less').default

In CommonJS, the default export is accessed via .default.

Quickstart

Basic Rollup config using rollup-plugin-less to compile .less files and output a CSS bundle.

// rollup.config.js
import less from 'rollup-plugin-less';

export default {
  input: 'src/main.js',
  output: {
    file: 'dist/bundle.js',
    format: 'es'
  },
  plugins: [
    less({
      insert: true,
      output: 'dist/styles.css'
    })
  ]
};