Runtime Platform APIs & Tooling
Every subchapter in this chapter, free to read online. Work through them in order, or jump straight to the runtime detail you need.
CLI Flags
How Node.js consumes startup flags, NODE_OPTIONS, preloads, V8 options, source maps, conditions, warnings, diagnostics, memory flags, node --run, and experimental config files.
.env Files
How Node.js loads .env files with --env-file, parses DotEnv syntax, resolves precedence, handles NODE_OPTIONS, uses process.loadEnvFile() and util.parseEnv(), and turns raw strings into validated config.
Web Platform APIs
How Node.js exposes web-compatible globals including fetch, Request, Response, Web Streams, Blob, File, FormData, URL, and structuredClone.
TypeScript & Compile Cache
How Node.js v24.15 runs TypeScript through type stripping, handles .ts module formats, rejects unsupported syntax, and stores compile cache data.
REPL, Inspector, Watch & SEA
How Node.js REPL, inspector sessions, watch mode, and single executable applications evaluate code, expose debugging state, restart, and package apps.