hardLow-Level Design

What is the 'vm' (Virtual Machine) module and when would you use it?

Q: What is the 'vm' (Virtual Machine) module and when would you use it?

**TL;DR.** node:vm compiles and runs JavaScript in a **separate V8 context** with its **own global object**, so the code doesn't see your module scope. It's useful for **isolating** dynamic code (templating, plugins, REPLs, config DSLs) — but it is **NOT a security sandbox** on its own; untrusted code can still escape and reach the host. host context your app + require/process vm context

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Tests advanced knowledge of sandboxed code execution in Node.

vmsecurityv8

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Run code in an isolated context with a timeout

import vm from 'node:vm';

const sandbox = { result: null, input: 21 };   // only these globals are visible
vm.createContext(sandbox);
vm.runInContext('result = input * 2', sandbox, { timeout: 50 });
console.log(sandbox.result);                    // 42

// ⚠ NOT safe for untrusted code — it can escape to the host.
// For that, use isolated-vm or a separate process/container.

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