Node.js

You might say

The terminal says command not found: node. Why can't my project run?

A runtime for JavaScript outside the browser, often used by local scripts and build toolsWhen a project specifies a Node.js version, use node -v in the terminal to check your local runtime. Node.js runs JavaScript outside the browser and can provide local capabilities such as file-system access; browser scripts run in a page environment, which is different.

Know first

JavaScript

Nodenode

The same .js file, run by a browser and by Node.js

script.js

const fs = require("fs");
const files = fs.readdirSync("./data");
console.log(`Read ${files.length} files`);

file:///Users/you/project/script.js

const fs = require("fs");
const files = fs.readdirSync("./data");
console.log(`Read ${files.length} files`);

The browser just shows the file as text; it does not run it

JavaScript commonly runs in browser pages or in Node.js in a terminal. npm runs on Node.js, and many project build commands use it; requirements depend on the toolchain.

Where Node.js sits in the toolchain

It is a runtime, not a new language: You still write JavaScript. Node.js adds the ability to execute it on a computer, so scripts run without opening a browser.

Build and package tools depend on it: npm and many project build commands use Node.js; whether a project needs it depends on its toolchain. Commands that rely on a missing Node.js installation report command not found.

Projects require specific versions: When docs say requires Node 18+, run node -v to see the local version; upgrade before running if it is too low.

You can say this to an AI Agent

The terminal reports command not found: node. First check whether Node.js is installed here and its version; if it is missing or below the project requirement, tell me which version to install, then rerun the project command and confirm it starts.

Learn next

1JavaScript→2Terminal→3npm→4Dependency→

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Following project docs, running npm start reports command not found: node. What should happen next?

A. Open the project entry file in a browser to run itB. Install Node.js, verify the version with node -v, then retryC. Re-clone the project and run the same command