Merge object settings.

Use object spread to apply JavaScript overrides to defaults.

JavaScript snippet.js
const settings = { ...{ theme: "light", size: 12 }, ...{ theme: "dark" } };
console.log(JSON.stringify(settings));

Expected output EXAMPLE

{"theme":"dark","size":12}

Details

Save as snippet.js and run node snippet.js. Uses built-in JavaScript and Node.js APIs; no npm dependencies are required.

Keep in mind

This is a shallow merge; nested objects are replaced.

✓ Verified

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
f45e29d22747f0333c84e04f7ad8df34a4e067fa8dd534902ed7b994c4b1bead
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

{"theme":"dark","size":12}

Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.