is-jeven

Checked, not fully reviewed. We ran its 7 tests (all pass) and called it with fetch mocked to return answers we chose. We did not ask Jev about any numbers.

isEven(n) sends { model: "jev-latest", state: { num: n }, questions: { category: … } } — a choice between "true" and "false" — to /v1/systemone, checks that the answer is a choice with one of those two values, and returns a boolean. It refuses anything that is not a safe integer before making a request (2 ** 60 is rejected locally), and a non-2xx response throws with the status code and nothing else.

The README calls it “a joke package FYI”, and its examples hedge accordingly: // true (probably). As a joke it is also a fair lesson in what not to copy. The answer’s probabilities are thrown away. A mocked answer at 0.6 for false came back simply as false, so the caller cannot tell a confident answer from a guess. That is the information Jev exists to give. And it is a question code answers exactly with n % 2 === 0.

MIT, 33 stars, on npm as is-jeven 1.0.1.

See how it compares with other tools in Best Jev tools, tested hands-on.

Review updated Oct 7, 2026. Numbers quoted from the project are its author's own; we don't publish our own measurements of Jev.