Detect on common react patterns, This is a combination of 12 commits.

Author: bounceme

ftdetect/javascript.vim

@@ -23,10 +23,20 @@ if g:jsx_pragma_required
   let b:jsx_pragma_found = search(s:jsx_pragma_pattern, 'npw')
 endif
 
+" if g:jsx_check_react_import == 1
+"   parse the first line of js file (skipping comments). When it has a 'react'
+"   importation, we guess the user writes jsx
+" endif
+let s:jsx_prevalent_pattern =
+      \ '\v\C%^\_s*%(%(//.*\_$|/\*\_.{-}\*/)@>\_s*)*%(import\s+\k+\s+from\s+|%(\l+\s+)=\k+\s*\=\s*require\s*\(\s*)[`"'']react>'
+
 " Whether to set the JSX filetype on *.js files.
 fu! <SID>EnableJSX()
   if g:jsx_pragma_required && !b:jsx_pragma_found | return 0 | endif
-  if g:jsx_ext_required && !exists('b:jsx_ext_found') | return 0 | endif
+  if g:jsx_ext_required && !exists('b:jsx_ext_found') &&
+        \ !(get(g:,'jsx_check_react_import') && search(s:jsx_prevalent_pattern, 'nw'))
+    return 0
+  endif
   return 1
 endfu