Node.js Modules Best Practices for Clean and Reusable Code
Modules are how you write clean Node.js code. Here are the best practices for using them well.
Node.js Modules Best Practices for Clean and Reusable Code
Modules are how you write clean, reusable Node.js code. Here are the best practices.
One Concern Per Module
Each module does one thing. A user controller handles user logic, not database connections and email sending. Focused modules are easier to test and reuse.
Export a Clear Interface
Export only what other files need. Keep internals private. A clear, minimal interface makes a module easy to use and hard to misuse.
Use Named Exports for Multiple Values
When exporting multiple things, use named exports: exports.add = fn; exports.subtract = fn. This makes the interface explicit and lets requiring files destructure what they need.
Default Export for Single Value
When exporting one main thing, assign to module.exports directly: module.exports = function() {}. This signals that the module has one primary export.
Pick One Module System
Use CommonJS or ES modules consistently. Mixing causes errors and confusion. Pick one per project and use it everywhere.
Avoid Side Effects on Require
A module should export, not do work on require. If a module sends an email or connects to a database just by being required, it is hard to test. Export a function that does the work instead.
The Takeaway
Use Node.js modules well by giving each one concern, exporting a clear minimal interface, using named exports for multiple values and a default for single, picking one module system, and avoiding side effects on require.
One concern per module, export a clear minimal interface, use named exports for multiple values and a default for single, pick one module system consistently, and avoid side effects on require so modules are easy to test.
Because a module that does work just by being required, like sending emails or connecting to a database, is hard to test and reason about. Export a function that does the work instead, so the work happens when you call it, not when you import it.
Use named exports (exports.add, exports.subtract) when exporting multiple values, so the interface is explicit and requiring files can destructure. Use a default export (module.exports = fn) when exporting one main thing, to signal it is the primary export.
Because focused modules are easier to test, reuse, and understand. A user controller that also sends emails and connects to databases is doing too much. One concern per module keeps each piece simple and its purpose clear.
Because a clear, minimal interface makes a module easy to use and hard to misuse. Internals stay private, so changes to internal code do not break other files. A module with 20 exports has a vague interface; one with 3 focused exports is clear.
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