Rollup Introduction

What is Rollup?

Rollup is a module bundler for JavaScript that compiles small pieces of code into something larger and more complex, such as a library or application. It is particularly well-suited for bundling ES modules.

Key Concepts

ES Modules: Rollup uses ES module syntax for imports and exports, allowing for tree-shaking.
Tree-shaking: This feature removes unused code from the final bundle, optimizing the output.
Plugins: Rollup has a rich ecosystem of plugins that can extend its functionality (e.g., Babel, CommonJS).

Installation

To install Rollup, you can use npm or yarn:

npm install --save-dev rollup

yarn add --dev rollup

Basic Usage

To create a basic Rollup configuration, create a file named rollup.config.js:


                export default {
                    input: 'src/index.js',
                    output: {
                        file: 'dist/bundle.js',
                        format: 'iife' // Immediately Invoked Function Expression
                    }
                };

Then, you can build your project with:

npx rollup -c

Best Practices

Keep your entry points minimal to improve build times.
Use plugins wisely to extend Rollup's capabilities without bloating your bundle.
Regularly analyze your bundle size and contents using rollup-plugin-visualizer.

FAQ

What file types can Rollup bundle?

Rollup primarily bundles JavaScript files but can also handle CSS, JSON, and other file types with the right plugins.

Can Rollup be used for React applications?

Yes, Rollup can be configured to work with React by using plugins like rollup-plugin-babel and rollup-plugin-node-resolve.

What is the difference between Rollup and Webpack?

While both are module bundlers, Rollup focuses on ES modules and tree-shaking, while Webpack supports a wider range of module types and features like hot module replacement.

Flowchart of Rollup Build Process


        graph TD;
            A[Start] --> B[Load Entry File];
            B --> C[Resolve Dependencies];
            C --> D[Transform Files with Plugins];
            D --> E[Bundle Modules];
            E --> F[Output Final Bundle];
            F --> G[End];