Introduction

Rollup.js is a popular JavaScript module bundler that is known for its fast build times and efficient code splitting capabilities. However, as your project grows, the build times can become slower. One way to address this issue is by implementing caching strategies in Rollup.js.

In this blog post, we will explore different caching strategies that you can use to speed up your Rollup.js builds and improve your development workflow.

Why do we need caching strategies?

Rollup.js calculates the dependencies and performs various optimizations every time it runs. This can be time-consuming, especially for larger projects with many dependencies. By implementing caching strategies, we can avoid repeating these calculations when the inputs have not changed, resulting in faster build times.

Caching strategies in Rollup.js

1. In-memory caching

Rollup.js provides an in-memory caching mechanism that stores the results of previous builds. This allows Rollup.js to skip unnecessary calculations and reuse the results, resulting in faster builds.

To enable in-memory caching in Rollup.js, you can use the cache option in your Rollup configuration file:

import { rollup } from 'rollup';

// Initialize the cache
const cache = {};

// Define your Rollup configuration
const inputOptions = {
  input: 'src/index.js',
  cache, // Pass the cache object
};

// Build your bundle
async function build() {
  const bundle = await rollup(inputOptions);
  
  // Update the cache with the latest results
  cache['src/index.js'] = bundle.cache;
  
  await bundle.write({
    file: 'dist/bundle.js',
    format: 'iife',
  });
}

build();

By persisting the cache object across builds using a file or a build tool like Gulp or Grunt, you can avoid recalculating dependencies and significantly reduce build times.

2. Plugin-level caching

In addition to in-memory caching, some Rollup.js plugins also provide their own caching mechanisms. For example, the rollup-plugin-babel plugin includes a caching option that can speed up the transpilation process.

To enable the caching option in the rollup-plugin-babel, you can pass cache: true in the plugin options:

import babel from 'rollup-plugin-babel';

// Define your Rollup configuration
const inputOptions = {
  input: 'src/index.js',
  plugins: [
    babel({
      cache: true, // Enable caching
    }),
  ],
};

// Build your bundle
async function build() {
  const bundle = await rollup(inputOptions);
  
  await bundle.write({
    file: 'dist/bundle.js',
    format: 'iife',
  });
}

build();

By leveraging plugin-level caching, you can avoid retranspiling files that haven’t changed and further speed up Rollup.js builds.

Conclusion

Caching strategies in Rollup.js can significantly improve your development workflow by reducing build times. The in-memory caching mechanism provided by Rollup.js and plugin-level caching options can help avoid unnecessary calculations and recompilations.

By implementing these caching strategies, you can enjoy faster build times and spend more time writing code instead of waiting for your builds to complete.

#rollupjs #buildoptimization