DataSag guides · Updated 27 October 2026

Load analytics without blocking rendering on Eleventy

Use the platform's non-blocking external script mechanism and install the tracker once. Measure the published page before and after the change; script size alone cannot predict the effect on your website. This guide applies to Eleventy.

Start with the Eleventy installation

Find the shared layout selected by your Eleventy data cascade, commonly an _includes/base.njk file. Add the deferred tracker to its head while preserving the content placeholder and existing template syntax. Build with your normal configuration and deploy the generated output. Layout paths depend on your project's directory settings.

Eleventy supports multiple template languages and chained layouts. A filename copied from an example may not be the active layout for your content. Inspect layout data and generated pages rather than assuming every collection uses the same wrapper.

Use the public project key from the DataSag project you are inspecting. A test on a preview domain does not confirm that the production domain has the same code or settings.

Load analytics without blocking rendering in Eleventy

  1. Keep the tracker deferred in the shared layout head and inspect post-render transforms for other copies. Preserve the public-key attribute when changing the tag; downloading a file without the key does not establish working measurement.
  2. Build the static site and measure the generated output using consistent network and cache settings. Include content produced through the normal transform pipeline so the measurement represents the final page served to visitors.
  3. Check an early primary-action click as well as a later reading interaction. If a custom loader waits for idle or another event, record which actions it misses. Eleventy build speed is separate from visitor-page loading performance.

The final generated page uses one deferred loader, with runtime timing and early-event coverage measured separately from build duration.

Complete the collection checks

  1. Record a baseline of the published page using the same browser, device emulation and network settings you will use for comparison. Include a representative content page, not only the homepage.
  2. Use defer for a normal external HTML script, or the framework-specific loading strategy shown in the installation example. Do not add a parser-blocking synchronous script as a shortcut.
  3. Keep one installation in the shared document or layout. Duplicate execution adds work even if the browser reuses the downloaded file.
  4. Inspect the Network waterfall for tracker.js and /api/track. Compare transfer size, timing and request count on a cold load and a cached load.
  5. Check that measurement still starts at the intended point. Loading only after idle or interaction can omit short visits and early clicks; performance and coverage must be evaluated together.
  6. Repeat the measurements and record variability. Report measured results for your page rather than claiming a universal speed improvement or zero performance cost.
// Browser Console, after loading the published page:
performance.getEntriesByType('resource')
  .filter(entry => entry.name.includes('/tracker.js'))
  .map(entry => ({ url: entry.name, durationMs: entry.duration }));
// Cross-origin transfer details may be unavailable.

What a successful check looks like

The script uses a non-blocking loading mechanism, appears once and records the intended visits. Any performance claim comes from repeatable measurements of the actual site.

Record the public path you tested, the browser state, the approximate time and the observed request. Check one direct page load and one later navigation so the result covers more than the homepage.

Common mistake

A faster lab result does not prove every visitor has a faster experience. Avoid mixing a warm-cache result with a cold-load baseline.

Installation snippet for Eleventy

The shared installation belongs in the head of the shared layout resolved from your includes directory. Use this as the installation reference while checking the procedure above.

<script defer src="https://www.datasag.com/tracker.js" data-datasag-key="YOUR_PUBLIC_KEY"></script>

Related Eleventy guides

Full Eleventy setup guide · Search and AI visibility

References

Official Eleventy documentation covers the integration point. For DataSag data handling, read the privacy policy. Use support if a request fails after these checks.