less-loader

What is less-loader?

The less-loader npm package is a loader for webpack that allows you to preprocess Less files into CSS. This enables developers to write styles in Less, a dynamic preprocessor style language that extends CSS with dynamic behavior such as variables, mixins, operations, and functions, and compile them into native CSS files that can be loaded into a web page.

What are less-loader's main functionalities?

Compiling Less to CSS

This feature allows you to compile Less files into CSS. The code sample shows how to configure webpack to use less-loader along with css-loader and style-loader to process `.less` files.

module.exports = {
  module: {
    rules: [{
      test: /\.less$/,
      use: [
        'style-loader',
        'css-loader',
        'less-loader'
      ]
    }]
  }
};

Importing Other Less or CSS Files

less-loader supports importing other Less or CSS files within a Less file. This feature enables code reusability and modularization. The code sample demonstrates importing a 'library' file and using a variable from it.

@import 'library';

.body {
  color: @baseColor;
}

Customizing Less Options

This feature allows the customization of Less compiler options through less-loader. The code sample demonstrates how to enable strict math and disable IE compatibility mode by configuring less-loader options in webpack.

module.exports = {
  module: {
    rules: [{
      test: /\.less$/,
      use: [
        'style-loader',
        'css-loader',
        {
          loader: 'less-loader',
          options: {
            lessOptions: {
              strictMath: true,
              noIeCompat: true
            }
          }
        }
      ]
    }]
  }
};

Other packages similar to less-loader

sass-loader

sass-loader is similar to less-loader but for compiling Sass/SCSS files into CSS. While less-loader focuses on Less files, sass-loader provides functionality for Sass, another popular CSS preprocessor language. Both loaders serve a similar purpose of integrating CSS preprocessing into webpack's build process.

stylus-loader

stylus-loader is designed for processing Stylus files into CSS, similar to how less-loader works with Less files. Stylus is another CSS preprocessor that offers syntax and features comparable to Less and Sass. The choice between less-loader, sass-loader, and stylus-loader typically depends on the specific preprocessor language a project uses.

postcss-loader

postcss-loader is a loader that allows you to use PostCSS, a tool for transforming CSS with JavaScript plugins. Unlike less-loader which is specific to Less, postcss-loader is more flexible and can be used to apply a wide range of transformations and optimizations to CSS files, making it a powerful tool in a developer's workflow.

README

less loader for webpack

Usage

Documentation: Using loaders

var css = require("!raw!less!./file.less");
// => returns compiled css code from file.less, resolves imports
var css = require("!css!less!./file.less");
// => returns compiled css code from file.less, resolves imports and url(...)s

Use in tandem with the style-loader to add the css rules to your document:

require("!style!css!less!./file.less");

webpack config

module.exports = {
  module: {
    loaders: [
      {
        test: /\.less$/,
        loader: "style-loader!css-loader!less-loader"
      }
    ]
  }
};

Then you only need to write: require("./file.less")

License

MIT (http://www.opensource.org/licenses/mit-license.php)