Rollup is a JavaScript module bundler designed to create small and optimized bundles for development. Rollup uses the same format as the ECMAScript module (ESM) and optimizes the bundle size by removing unnecessary code. Rollup helps to bundle your Javascript code into a single file or multiple files, optimizing the size and performance of your application. Rollup is known for its tree-shaking capability, eliminating unused code from your bundle, resulting in smaller file sizes. It’s a great tool for building efficient and optimized JavaScript applications.
Key Features of Rollup
Rollup has many powerful features, making it an excellent choice for bundling JavaScript applications. Here's an overview of some of its standout capabilities:
Advanced Code Splitting and Tree Shaking: Rollup offers advanced code-splitting and tree-shaking capabilities, allowing developers to split their code into smaller chunks for efficient loading. It improves resource management and initial load times. Rollup's robust tree shaking eliminates unused code from the final bundle by analyzing the dependency graph, resulting in smaller bundle sizes and improved performance.
Wide Range of Plugins for Extendability: Rollup has a rich ecosystem of plugins that extend its functionality and cater to various development needs. These plugins cover many functionalities, including CSS preprocessing, asset optimization, code transformation, and integration with other tools and frameworks. Developers can easily enhance Rollup's capabilities by leveraging existing plugins or creating custom ones tailored to their requirements.
Optimized Output for Smaller Bundles: Rollup is designed to generate optimized output for smaller bundles, particularly in production builds. It employs various optimization techniques, such as minification, compression, and code splitting, to reduce the size of the generated bundles. This results in faster loading times and improved end-user performance, especially on bandwidth-constrained networks.
Focus on ES Module Bundle Efficiency: Rollup strongly emphasizes optimizing the efficiency of ES module bundles. It leverages native ES module support and modern JavaScript features to generate highly optimized bundles. Rollup's ES module bundling approach ensures that only the necessary code is included, leading to faster loading times and better overall performance.
Comparison of Vite and Rollup
Vite and Rollup are powerful tools for web development, each with its own focus and core strengths, especially when bundling and building web applications. Here’s a comparison of the two to highlight their differences:
Development Experience
Vite provides a faster development experience leveraging modern browser capabilities like the instant HMR, which lets you see real-time changes without refreshing the page. It doesn’t require you to bundle your application during the development process.
Rollup, on the other hand, primarily focuses on creating optimized production builds. While it can also be used for development, its core strengths lie in its ability to bundle and process production build, improving performance and optimizing the application.
Tree Shaking
Vite prioritizes rapid development, offering fast refresh and build times while also incorporating tree-shaking to optimize production builds by discarding unused code, thanks to its utilization of Rollup's robust tree-shaking functionality.
On the other hand, Rollup is well known for its ability to remove unnecessary code efficiently and ensure that the final bundles are lean and optimized, contributing to improved performance and smaller bundle sizes. For example, when instead of importing the whole utils object, we can decide only to import the ajax function we need:
import { ajax } from './utils';
const query = 'Rollup';
ajax(`https://api.example.com?search=${query}`).then(...);
Framework Support
Vite has built-in support for Vue.js, React, and more frameworks. It’s designed with modern frameworks in mind, so it caters to all modern front-end frameworks, making it a popular choice for Vue projects. Vite’s flexibility and ease of use make it a go-to choice for projects utilizing these modern frameworks.
// vite.config.js
import vue from '@vitejs/plugin-vue'
export default {
plugins: [vue()],
}
In contrast, Rollup offers a framework-agonist approach, which means it can be configured to work with any framework. It does not offer the same level of compatibility with modern frameworks, and it may require more setup than Vite to get it up and running. However, for projects focused on creating libraries, its configurability may be a good advantage as it allows you to add specific customizations for your build process.
Community and Ecosystem
Both Vite and Rollup have active communities and growing ecosystems. Vite is newer and gaining popularity, especially within the Vue.js community. Rollup has been around longer and has a mature ecosystem with many plugins and integrations.
Popularity
Rollup excels at reducing bundle sizes and improving performance, making it popular for libraries and smaller projects. Vite, a widely recognized and extensively documented tool, is known for its versatility in handling various file types and strong community support. The npm trends graph below shows the number of downloads Rollup has over Vite in the past year. Rollup has more downloads than Vite, possibly due to several reasons, including project use cases and the year the package was created.