CURATED CODEX

Node.js Interview Questions

Q: What is npm, and what problem does it solve for a Node.js project?

npm (Node Package Manager) is both a CLI tool and a public registry that solves dependency management for JavaScript projects: instead of manually downloading and wiring up third-party libraries, you declare them in `package.json` and run `npm instal

Q: What is the purpose of the package.json file, and what key information does it hold?

`package.json` is the manifest file for a Node.js project - it's the single source of truth npm (and tooling like bundlers, CI systems, and other developers) reads to understand what the project is and how to work with it. Key fields: `name` and `ver

Q: What is the difference between module.exports and exports in a CommonJS module?

`module.exports` is the actual object that `require()` returns to the caller. `exports` is simply a variable that Node initializes to point at the same object as `module.exports` - it's a convenience reference, not a separate mechanism. You can safel

Q: What does "non-blocking I/O" mean in the context of Node.js?

Non-blocking I/O means that when Node.js starts an I/O operation (reading a file, querying a database, making a network request), it doesn't halt the thread and wait for it to finish. Instead, it registers a callback, hands the operation off (to the

Curated real-world Node.js interview questions focusing on event loop phases, microtasks vs macrotasks, worker threads, streams, backpressure, IPC, memory profiling, and high-concurrency server architectures.

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What is Node.js and how does it differ from running JavaScript in a browser?

Node.js is a server-side JavaScript runtime built on Google's V8 engine that lets you run JavaScript outside a browser - on a server, in a CLI tool, or in a build script. The key difference is the environment/API surface, not the language: browser JS has window, document, and DOM APIs for manipulating a page; Node.js has no DOM at all, but instead exposes OS-level APIs through core modules like fs (filesystem), http (networking), path, and process. Browser code runs in a sandboxed, per-tab context with no direct file or OS access (for security); Node.js code runs with the full privileges of the user executing it. A common interview follow-up is 'what's the global object in Node?' - it's global, not window. Both share the same core JavaScript language (ES features, closures, prototypes) because both ultimately execute on V8 (Node also uses libuv for async I/O, which browsers don't need in the same way).

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Differences between Node.js and the Browser | Node.js Learn Top 50 Node.js Interview Questions and Answers (2026) - StackInterview

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What is npm, and what problem does it solve for a Node.js project?

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What is the purpose of the package.json file, and what key information does it hold?

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What is the difference between module.exports and exports in a CommonJS module?

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What does "non-blocking I/O" mean in the context of Node.js?

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