What are circular dependencies in Node.js and how do you handle them?
When A requires B and B requires A. Node.js returns a partially loaded module, which can cause bugs. Avoid by restructuring so dependencies go one way, or use lazy require inside functions so the require happens when the function runs, not on load.
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More FAQs in Node.js Modules Interview Questions With Answers
exports is a reference to module.exports initially. You can add properties to exports or reassign module.exports. Mixing both breaks the link, since reassigning module.exports makes exports point to the old object. Pick one approach per file.
require reads a file, runs it once, caches the result, and returns the file's module.exports. Subsequent requires return the cached object without re-running the file, so a module's code runs once.
Modules run once and are cached after first require. This enables singletons for shared state like database connections, but means requiring the same file twice returns the same object. Export a factory function for fresh state on each use.
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