Browser script

The browser script is the default source created with every new site. It targets under 1.5 kB gzipped, has zero dependencies, and uses no cookies, localStorage or sessionStorage.

Install

<script
  defer
  src="https://cdn.metrikstack.com/js/script.js"
  data-site="SITE_ID"
></script>

See Quickstart for the full walkthrough, including proxying the script through your own domain.

What it tracks

On load, and on every SPA navigation, it sends:

path, referrer
screen size, language
utm_* query parameters (everything else is stripped)
the merge request_id, if one is present (see How merging works)
the navigator.globalPrivacyControl flag (gpc), recorded but never used to drop the event

On visibilitychange / pagehide it sends a leave event carrying time on page and scroll depth, via sendBeacon so it survives the tab closing.

SPA support

The script patches history.pushState and listens for popstate, so client-side route changes in React/Vue/Svelte-style SPAs are tracked as pageviews without any extra integration code.

Custom events

<script>
  window.metrikstack.track('signup', { plan: 'pro' });
</script>

track(name, props?) sends a custom event with the given name and an optional flat object of string properties, associated with the current page and merge request_id.

A second, opt-in script tag adds uncaught-exception capture on top of this one: data-errors plus a captureException helper, grouped into issues in the dashboard. It ships as a separate file so sites that don't want it pay nothing for it. See Errors for the tag, the API and what is and isn't collected.

Local development

By default the script does nothing on localhost or file: origins, so local testing doesn't create noise in production data. Opt back in with:

<script
  defer
  src="https://cdn.metrikstack.com/js/script.js"
  data-site="SITE_ID"
  data-allow-local
></script>

Reading the merge request id

If your server or edge already sets a request id (see How merging works), the script picks it up automatically: first from <meta name="metrikstack-request-id">, falling back to performance.getEntriesByType('navigation')[0].serverTiming (which survives CDNs that strip response headers before they reach the browser but pass Server-Timing through). No configuration is required on the script's side.