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diff --git a/chromium/docs/website/site/blink/platform-predictability/compat-tools/index.md b/chromium/docs/website/site/blink/platform-predictability/compat-tools/index.md deleted file mode 100644 index 6c0dd743a9c..00000000000 --- a/chromium/docs/website/site/blink/platform-predictability/compat-tools/index.md +++ /dev/null @@ -1,163 +0,0 @@ ---- -breadcrumbs: -- - /blink - - Blink (Rendering Engine) -- - /blink/platform-predictability - - Web Platform Predictability -page_name: compat-tools -title: Web compat analysis tools ---- - -When deprecating or changing web-exposed behavior, it's often important to get a -clear understanding of the compatibility impact. We have a variety of tools -available to you depending on the scenario. This page is designed to help you -choose the appropriate tool (in decreasing order of usage). For questions and -discussion, e-mail -[feature-control@chromium.org](https://groups.google.com/a/chromium.org/forum/#!forum/feature-control). - -## UseCounter - -[UseCounter](https://chromium.googlesource.com/chromium/src/+/HEAD/docs/use_counter_wiki.md) -is a framework in Blink which is used to record per-page anonymous aggregated -metrics on feature usage, often via the [\[Measure\] idl -attribute](https://chromium.googlesource.com/chromium/src/+/HEAD/third_party/blink/renderer/bindings/IDLExtendedAttributes.md#Measure_i_m_a_c). -Results are shown publicly on -[chromestatus.com](https://www.chromestatus.com/metrics/feature/popularity) (for -the [dominant milestone per -day](https://github.com/GoogleChrome/chromium-dashboard/issues/279)) . More -detailed break-downs are available to Google employees via the -[Blink.UseCounter.Features histogram using a formula with the PageVisits bucket -in the denominator](https://goto.google.com/uma-usecounter). Internally it's -also possible to look at UseCounter by the [fraction of users that hit it at -least once in a day](https://goto.google.com/uma-usecounter-peruser), and -UseCounters [hit within Android -WebView](https://goto.google.com/uma-usecounter-webview). In the vast majority -of cases, compat tradeoffs are made entirely based on public UseCounter data. - -**Pros:** - -* Reflects real Chrome usage - should be the primary source of all - compat discussions in blink -* Has huge coverage - reflects a wide fraction of all usage of Chrome - -**Cons:** - -* Requires at least a couple weeks to get any useful data (several - months to roll out to stable) -* Biased against scenarios where UMA tends to be disabled more often - (eg. enterprises) -* Can't be publicly used to get specific URLs. However, Googler's are - starting to be able to do this internally with - [CrUX](https://developers.google.com/web/tools/chrome-user-experience-report/) - data ("UKM"). While limited for privacy reasons, it's already - proving quite useful. - -## Simple web search - -Often it's useful to find examples of specific coding patterns in order to -understand the likely failure modes and formulate migration guidance. Use -technical web search engines like [nerdydata.com](https://nerdydata.com), or for -problems in specific libraries, ranking sites like -[libscore.com](https://libscore.com). - -**Pros:** - -* Simple, easy to use -* Results in specific URLs for further analysis - -**Cons:** - -* Strictly a dumb static search, can't reliably find all uses of an - API (especially due to Javascript minifiers which generate code like - "a\[b\]()"). - -## The HTTP Archive - -A slightly more advanced form of static web search is to use the [HTTP -Archive](http://httparchive.org/), a database of the top 500k websites, updated -by a crawl twice a month. See [HTTP Archive for web compat decision -making](https://docs.google.com/document/d/1cpjWFoXBiuFYI4zb9I7wHs7uYZ0ntbOgLwH-mgqXdEM/edit#heading=h.1m1gg72jnnrt) -for details on using it for compat analysis. - -**Pros:** - -* Can provide an absolute measure of risk ("only 10 sites in the top - 500k appear to use this API"). -* Now [includes UseCounter - data](https://groups.google.com/a/chromium.org/forum/#!topic/blink-api-owners-discuss/uxwEuxCRfGA), - so can go beyond simple static search to some dynamic behavior - -**Cons:** - -* Only captures behavior triggered during page load -* Only reflects the home page of the top 500k sites -* Analysis is more involved - -## Microsoft's CSS Usage Data - -[CSS usage on the web -platform](https://developer.microsoft.com/en-us/microsoft-edge/platform/data/) -is "from a Bing-powered scan" of lots of pages, and measures both CSS properties -and values. (Chrome use counters generally don't exist for values.) - -## GitHub and stackoverflow deprecation warning search - -Once a deprecation warning has been landed (or made it to stable), it can be -[extremely -informative](https://groups.google.com/a/chromium.org/forum/#!topic/intervention-dev/_0eSO-NjULo) -to search [GitHub](https://github.com/) issues (or other developer help sites -like [stackoverflow.com](https://stackoverflow.com/)) for discussion of the -warning generated on the console (eg. by searching for the chromestatus ID -present in the warning). - -**Pros:** - -* Helps identify the real-world pain experienced by developers -* Provides an avenue for outreach, and can [build - goodwill](https://twitter.com/jgwhite/status/832517528899448832) - -**Cons:** - -* Long turn-around time -* Lossy - absence of signal doesn't really indicate an absence of risk - -## GitHub code search - -Most of the popular libraries and frameworks are present on GitHub. -[Searching](https://github.com/search) for potentially impacted code can be -useful in better understanding the risk. - -**Pros:** - -* Provides unobfuscated access to code -* Provides an avenue to engage with developers to better understand - their use cases and their ability to apply mitigations. - -**Cons:** - -* Doesn't provide much signal on magnitude of impact -* Supports only either simple static searches. - -## On-demand crawl - -Occasionally it's useful to search top sites for a specific behavior (without -landing a UseCounter and waiting for the data to show up in HTTP Archive). For -advanced cases like this we can run a custom chromium build on the [telemetry -cluster](/developers/cluster-telemetry) to crawl the top 10k (or more) sites and -record whatever we like (with a temporary UseCounter). See [Using Cluster -Telemetry for UseCounter -analysis](https://docs.google.com/document/d/1FSzJm2L2ow6pZTM_CuyHNJecXuX7Mx3XmBzL4SFHyLA/edit#) -for details. - -**Pros:** - -* Can have fast turn-around time (hours) -* Usually used just for page load, but can be extended to trigger - other interactions (scroll, clicking on links, etc.). - -**Cons:** - -* Limited scope -* Complicated and brittle. Relies on some changes to telemetry that - cannot currently be landed. Generally found not to be worth the - effort compared to the alternatives above.
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