Clean up a generator after an early break.

JavaScript: Breaking a for-of loop closes a generator and runs its finally block.

function* values() {
  try { yield 1; yield 2; }
  finally { console.log("closed"); }
}
for (const value of values()) {
  console.log(value);
  break;
}

Expected output EXAMPLE

1
closed

Details

Save as snippet.js and run node snippet.js. Uses built-in Node.js and JavaScript APIs. Breaking a for-of loop closes a generator and runs its finally block.

✓ Verified

Tested on Ubuntu 24.04.5 LTS · 2026-11-02 18:08:39 UTC · 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: 8c5b470724df7f33578a109f3ce478cb25f3db6806fc81bf4b4eaa129b5c86e0
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

1
closed

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