Write a UTF-8 file.
Use the built-in Node.js filesystem API to save text.
const fs = require("node:fs");
fs.writeFileSync("notes.txt", "hello\n", "utf8");
console.log("Saved notes.txt");Expected output EXAMPLE
Saved notes.txt
Details
Save as snippet.js and run node snippet.js. Uses built-in JavaScript and Node.js APIs; no npm dependencies are required.
Node.js only; this replaces an existing file and blocks until complete.
Tested on Ubuntu 24.04.5 LTS · · v18.19.1 · nodejs 18.19.1+dfsg-6ubuntu5
Test inputs, results and environment
The exact published code ran in a dedicated Linux test container with prepared inputs. Unprivileged snippet process, external networking disabled, read-only root filesystem, and a fresh temporary working directory. Fixtures and output records are isolated from the application database. Testing covers this example and its stated checks, not every input, operating system, or runtime version. The Linux container shares its host's kernel; this is not a native Windows test.
- Architecture / host kernel
- x86_64 / 6.18.54.1-microsoft-standard-WSL2
- Snippet identity / locale
- uid=65534, gid=65534 (unprivileged) / C.UTF-8
- Interpreter invocation
node snippet.js- Container image ID
sha256:32dc2d998158b6554c99b73b533f423696a0f3e31e8cbea9db10b5eee9a2fadd- Code SHA-256
6ff5a59049a9b48bec467036c5b1e6da910bd6f6243d544bac7835a3ebf5990f- Dependencies
- nodejs 18.19.1+dfsg-6ubuntu5
Test input setup
These are the prepared inputs used by the test harness. See Details above for the prerequisites and how to run this example.
# No input files required.
Observed standard output
Saved notes.txt
Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.
Additional assertions that passed
Checks recorded by the test harness. Where Python assertions are shown, browser cases use Playwright and simulator cases may inspect pin transitions: result.stdout is captured output, work is the temporary directory, and Path is pathlib.Path. The harness also imports json and csv.
assert Path('notes.txt').read_text() == 'hello\n'