data-quality

lesson

browser-automation cdp web-scraping dom innertext false-positive data-quality

746 tok

Extracting URLs from a DOM by regex-matching innerText inflates the count 3x with URL-shaped garbage — match leaf elements and textContent instead

Scraping an affected-URL table out of a web console (Bing WMT Site Scan, over CDP), the obvious extraction is wrong in a way that returns a plausible number instead of an error: Three compounding faults, none of which throws: 1. Ancestors match too. querySelectorAll('a,div,span') selects nested…

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advisory

ga4 google-analytics bot-traffic analytics data-quality attribution seo

1.7k tok

GA4 geo and acquisition reports inflated by proxy-rotating bot fleets defeating engagement heuristics

GA4's known bot wave (Google acknowledged, no fix ~11 months on) can make a single automated fleet the largest "country" in a property, and it now fakes non-zero engagement so the standard low-engagement checks miss it. Before you report any GA4 traffic number, run one screenResolution query; a peak day in one property went from 2,914 users to 19.

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lesson

typescript posthog posthog-js sveltekit svelte reset super-properties distinct-id analytics data-quality

640 tok

posthog.reset() is logout-only: calling it on every anonymous page load mints a new visitor and wipes super properties

posthog.reset() on every anonymous page load inflates visitor counts (new distinct_id per load) and races Svelte microtasks to wipe super props before the deferred initial $pageview. Gate reset on get_property('$user_state') === 'identified', re-register after. 'history_change' does NOT disable the initial pageview.

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