Don’t track prerendered pages about fathom HOT 2 CLOSED

Great tip, thanks @da2x.

Looking at MDN and caniuse, I can't seem to find anything on document.visibilityState not having the prerender value in Firefox or Safari. Could you shed some light on that for me please?

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@dannyvankooten, my only data point is my own custom tracker. It submits onpageunload and checks ('visibilityState' in document && document.visibilityState=='prerender') before doing a sendBeacon(). I still see X-Moz and X-Purpose headers with the submissions despite the check.

I saw a 1,8 % decline in pageviews when I started filtering out prerendered pages. If I remember correctly, there is Google documentation somewhere out there (couldn’t find it now) suggesting about 0,5–1,5% of Chrome pageviews are prerendered and never seen by a human.

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