Question 1

What is the difference between spawn() and exec() in Node.js?

Accepted Answer

The main difference is that `spawn` runs a process and streams its output in real-time, making it ideal for large volumes of data or long-running processes. Conversely, `exec` runs a command in a shell and buffers the entire stdout/stderr output before returning it in a callback, which can fail if the buffer size exceeds its limit (default 1024KB). Use `spawn` for streaming data and `exec` for running simple commands with small execution outputs.

Question 2

Explain the differences between fork(), spawn(), and exec() in the child_process module.

Accepted Answer

**Target Audience:** Engineers preparing for Node.js interviews — assumes basic `child_process` familiarity. **Difficulty:** Medium > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. All three functions below were **actually run** on Node v24.19.0, including a real `fork()` IPC message round-trip. ## 1. Why This Even Matters — A Story First Three ways to get help from someone in another room: shout a short instruction

Question 3

What is the Node.js permission model (--permission) and what does it protect against?

Accepted Answer

**Target Audience:** Engineers preparing for Node.js security and runtime-sandboxing interviews. **Difficulty:** Hard > **How to read this doc:** Concepts are explained in plain language first, then tagged with 📌 Interview term:. The blocked and allowed file reads below were **actually run** with a real `node --permission` process — a genuine, specific error for the unlisted path, not a description of documented behavior. ## 1. Why This Even Matters — A Story First A hotel guest

NODE.JSDECODED.

Medium

What is the difference between spawn() and exec() in Node.js?

Explain the differences between fork(), spawn(), and exec() in the child_process module.

Hard

What is the Node.js permission model (--permission) and what does it protect against?