Browser support

f.js is built to target ES2018, which sets a practical floor of:

• Safari 12+
• Chrome 66+
• Firefox 60+
• Edge 79+ (Chromium-based Edge)

This covers nearly all real traffic. These versions are years old, but the next section covers what happens for the small tail of visitors on something older.

What happens below the floor

f.js is a single JavaScript file, and a browser that doesn't support ES2018 syntax cannot parse it. The <script> tag fails to execute, but nothing else on the page is affected, and no page-breaking error is thrown. The result is a graceful no-op: the banner does not render, window.consentfolio is never defined, and any script gated behind data-cf-consent or a dashboard-configured category stays inert, because nothing ever grants it consent.

This is the same fail-closed outcome as an ad blocker preventing f.js from loading (see adblock-itp.md): non-essential scripts never activate without a recorded grant of consent. Below the browser floor you lose the banner and any chance of that visitor consenting, but compliance still holds because nothing non-essential runs without a recorded grant.