Outbound links Pro

Capture clicks on any anchor that points to a different hostname. Useful for measuring traffic you send to other domains: affiliate links, social share buttons, links out to your GitHub, npm, or documentation on a separate subdomain.

Enable

init

init("proj_xxx", { extensions: { outboundLinks: true } })

// or, in React:
<Analytics projectId="proj_xxx" extensions={{ outboundLinks: true }} />

What fires

One outbound_click event per matched click, with three properties:

Property Example Notes

url https://github.com/clamp-sh/clamp Full resolved URL, including path and query.

host github.com Hostname only. Use this to group by destination.

pathname /clamp-sh/clamp Path portion of the destination URL.

Property	Example	Notes
`url`	`https://github.com/clamp-sh/clamp`	Full resolved URL, including path and query.
`host`	`github.com`	Hostname only. Use this to group by destination.
`pathname`	`/clamp-sh/clamp`	Path portion of the destination URL.

What counts as outbound

Any anchor whose resolved hostname differs from location.hostname. Subdomains count as different hosts — a click from clamp.sh to app.clamp.sh fires.
Relative URLs are resolved against the current page with new URL(href, location.href), so they always match the current hostname and are never outbound.
Only http: and https: protocols are tracked. mailto:, tel:, javascript:, and custom schemes are skipped.
Anchors without an href attribute are skipped. Button elements are never matched — only <a>.

How it works

A single delegated click listener is attached to document in the capture phase, so it runs before any stopPropagation further down the tree. On click, the SDK walks up the DOM from the target using closest("a"). One listener per page regardless of how many links exist — cheap.

Gotchas

Subdomains are treated as different hosts. If that’s wrong for your setup, don’t enable this extension and instead track cross-property clicks with explicit track() calls.
Navigation triggered by JavaScript (window.open, location.href = ...) never fires. This extension only captures real <a> clicks.
Right-click “open in new tab” does fire — it dispatches a click event. Middle-click and Cmd/Ctrl-click also fire.
Every outbound click costs one event against your monthly quota. Busy pages with many external links can consume quota quickly; estimate before enabling on high-traffic pages.