Commits on Jun 15, 2020

1. Cache detected React version …

   I've been timing and profiling ESLint runs at Airbnb and noticed that
   react/no-unknown-property is particularly slow for us when using the
   "detect" setting for React version.
   
   When running ESLint using TIMING=1 on a directory that contains about
   500 files to be linted in it, react/no-unknown-property shows up as
   taking about 1700ms.
   
   Looking at the callstacks in the profiler, it seems that when this rule
   calls getStandardName for every JSXAttribute here, it will actually do
   all of the work to detect the React version every time to determine the
   correct set of DOM property names. Since there may be a lot of
   JSXAttribute nodes in a codebase, this adds up to quite a bit of work.
   
   By specifying the react version in our ESLint config, the
   no-unkown-property rule drops out of the top 10 slowest rules entirely,
   with the 10th slowest clocking in at 180ms.
   
   I think it would be a good idea to cache the React version when using
   detect instead of looking it up every time.

   

   lencioni committed Jun 15, 2020
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