require() vs import: a friendly guide for small teams Pick the right JavaScript module style and move forward without the drama
Intro
Modules are just a way to split your code into tidy, reusable pieces — like folders for your ideas. For many small businesses and solo founders, the choice between require() (CommonJS) and import (ES Modules) can feel like a technical rabbit hole. But it only becomes a problem when it blocks shipping, slows builds, or causes mysterious runtime errors. This guide strips it down to what matters: compatibility, migration risk, and simple steps to switch when it helps your product. No deep developer jargon — just practical decisions you can make between features, performance, and tooling.
Where most people go wrong
Assuming the latest option is always better. Newer (ES Modules) has benefits, but legacy packages or build tools may force a slower transition.
Trying to migrate everything at once. Large, untested changes cause outages; doing it incrementally avoids surprises.
Ignoring file extensions and package.json settings. Small config misses (like "type":"module") are the source of most import/export errors.
Main framework: a 4-step plan you can actually follow
Audit first
List critical apps and dependencies that must keep working (payment flows, auth, integrations).
Check whether key packages offer ESM builds or are CJS-only.
Tip: start with code that’s easy to test (utility libraries, internal components).
Choose your baseline
New projects: pick ES Modules (import/export) when using modern tools (Vite, Rollup, modern Node).
Legacy or compatibility-first projects: keep CommonJS (require/module.exports) until you can update dependencies.
Tip: prefer ESM for long-term maintainability; CJS for quick fixes or older stacks.
Migrate incrementally
Convert one module, ship tests, and deploy. Keep failing or legacy parts isolated as .cjs files or in a separate package until stable.
Use dynamic import() for lazy-loading or when you can’t swap to static imports yet.
Tip: set "type":"module" in package.json only after testing a subset, or use .mjs/.cjs to mix safely.
Test, observe, repeat
Add CI checks and monitor error logs after each change.
Update build-tool configs (Babel, Webpack, Vite) so bundlers preserve tree-shaking or transpile as needed.
Tip: watch for missing file extensions and issues with __dirname in ESM — there are straightforward workarounds.
Short case study
A solo founder running a small SaaS swapped a backend microservice from CommonJS to ES Modules to improve bundle size and use top-level await during startup. They: - Added tests and a feature branch. - Converted three utility files and updated package.json to "type":"module" after confirming their auth library supported ESM. - Kept legacy scripts as .cjs until all deps were updated. Result: faster cold starts and simpler async initialization — with zero customer-facing downtime.
Want a step-by-step walkthrough? We’ve written practical notes and examples on the blog: https://prateeksha.com/blog?utm_source=tumblr and a focused comparison here: https://prateeksha.com/blog/difference-between-javascript-require-vs-import?utm_source=tumblr
FAQs
Q: Will switching break my users? A: Not if you test and migrate incrementally. Breakage usually comes from untested changes or incompatible dependencies.
Q: Do I need to update Node to use import? A: Modern Node versions support ESM well. Check your Node version and follow package.json or .mjs/.cjs conventions.
Q: Should I convert third-party packages? A: No — prefer replacing or wrapping them. Many packages publish both CJS and ESM builds.
Q: What about performance? A: ESM enables tree-shaking and better bundler optimizations, which often yields smaller, faster client bundles.
Conclusion
Start by auditing your critical paths and dependencies — don’t guess.
Prefer ES Modules for new projects; keep CJS for legacy compatibility.
Migrate one piece at a time, test in CI, and monitor after deploys.
If you want help planning a migration or reviewing your build, check the practical resources at https://prateeksha.com?utm_source=tumblr
Ready to make the switch without the stress? Read more tips and examples on our site and blog: https://prateeksha.com/blog?utm_source=tumblr and the focused guide at https://prateeksha.com/blog/difference-between-javascript-require-vs-import?utm_source=tumblr — or reach out and we’ll walk through your codebase with you.