In connection with the thread on webkitPostMessage, I took a look at what sorts of metrics we have currently for depreciated features. We have high quality data for two groups of APIs:
For mutation events, we measure what percent of Documents have listeners for various kinds of mutation events: DOMAPI.PerDocumentMutationEventUsage.DOMCharacterDataModified: 2.85% of all Documents DOMAPI.PerDocumentMutationEventUsage.DOMNodeInserted: 4.78% of all Documents DOMAPI.PerDocumentMutationEventUsage.DOMNodeInsertedIntoDocument: 0.21% of all Documents DOMAPI.PerDocumentMutationEventUsage.DOMNodeRemoved: 0.07% of all Documents DOMAPI.PerDocumentMutationEventUsage.DOMNodeRemovedFromDocument: 0.0003% of all Documents DOMAPI.PerDocumentMutationEventUsage.DOMSubtreeModified: 2.30% of all Documents >From this data, it's tempting to remove support for DOMNodeRemoved and DOMNodeRemovedFromDocument as those are used extremely rarely. We don't have any data for how much of this usage is attributable to extensions. It will be interesting to watch this data as we evangelize MutationObservers, especially among extension developers. Another metric we have is for Blob.webkitSlice: Ratio of Blob.webkitSlice calls to Blob.slice: 14.87% Ratio of Blob.webkitSlice calls to Document creation: 0.0053% It's difficult to know how to interpret this data because we don't actually correlate calls to webkitSlice with Documents or Pages. Instead, we just count the total number of calls across all Documents. This gives us an upper bound on how many Documents (or Pages) would be affected by deleting Blob.webkitSlice, but doesn't measure that information as accurately as the data we have for mutation events. We are also gathering metrics on the usage of vendor prefixes in CSS properties, but that histogram doesn't appear to have been in the field long enough to have meaningful data. Adam _______________________________________________ webkit-dev mailing list webkit-dev@lists.webkit.org http://lists.webkit.org/mailman/listinfo/webkit-dev
