// the take
appmetrics.js is a tiny wrapper around the browser's User Timing API that lets you mark the start and end of an event, log the duration, and optionally push it to Google Analytics as a User Timing event. It's aimed at developers who want lightweight custom perf instrumentation in a pre-Core-Web-Vitals, pre-GA4 web stack.
The API itself is clean: a Metric object with start()/end()/log()/sendToAnalytics(), fully chainable, and it rides on performance.now() and the native User Timing marks so measurements show up directly in the DevTools timeline and WebPageTest without any extra tooling. Zero dependencies and genuinely tiny (under 1kb gzipped), so the cost of adding it is negligible.
Last commit was January 2018 — this is unmaintained, and the one thing the library is built to do, report to Google Analytics, is now broken for most users: Universal Analytics (and its User Timing reports under Behavior > Site Speed) was sunset in 2023, and GA4 has no equivalent sendToAnalytics target, so the core feature doesn't work against a current GA property. Install instructions lead with Bower, which has been dead for years, and there's no TypeScript definitions or ESM build, just a prebuilt dist/appmetrics.min.js from the gulp era. Anyone wanting this today is better served by the Performance Observer API directly or a modern RUM library.
We read the README, the directory tree and a key source file in October 2026. Nobody pays to be listed. How we judge →