What is the Node.js path module?

Direct answer

The path module joins, resolves, and normalizes file paths in an OS-aware way — use path.join and path.resolve instead of string concatenation to avoid broken paths on Windows vs POSIX.

Hardcoding foo/bar/baz breaks on Windows backslashes. path.join uses the correct separator for the current platform.

Method	Use
path.join(...parts)	Safe concatenation — ignores extra slashes
path.resolve(...parts)	Absolute path from cwd + segments
path.basename(p)	File name — config.json
path.dirname(p)	Parent directory
path.extname(p)	Extension — .json
path.parse(p)	Object with root, dir, base, ext, name

Security — path.join upload dir + user input can escape via .. — validate with path.resolve and prefix check (Q66).
posix vs win32 — path.posix.join for URLs; path.win32 on Windows-specific tools.

path-examples.mjs

import path from "node:path";
import { fileURLToPath } from "node:url";

const __dirname = path.dirname(fileURLToPath(import.meta.url));

const dataFile = path.join(__dirname, "data", "interviews", "nodejs");
const absolute = path.resolve("./config", "app.json");

console.log(path.basename(dataFile)); // nodejs
console.log(path.extname(absolute));   // .json