Improved performance of jsRegexpString

Author: amadeus

syntax/javascript.vim

@@ -95,7 +95,7 @@ syntax match   jsRegexpOr         "\v\<@!\|" contained
 syntax match   jsRegexpMod        "\v\(@<=\?[:=!>]" contained
 syntax cluster jsRegexpSpecial    contains=jsSpecial,jsRegexpBoundary,jsRegexpBackRef,jsRegexpQuantifier,jsRegexpOr,jsRegexpMod
 syntax region  jsRegexpGroup      start="\\\@<!(" skip="\\.\|\[\(\\.\|[^]]\)*\]" end="\\\@<!)" contained contains=jsRegexpCharClass,@jsRegexpSpecial keepend
-syntax region  jsRegexpString     start=+\(\(\(return\|case\)\s\+\)\@<=\|\(\([)\]"']\|\d\|\w\)\s*\)\@<!\)/\(\*\|/\)\@!+ skip=+\\.\|\[\(\\.\|[^]]\)*\]+ end=+/[gimy]\{,4}+ contains=jsRegexpCharClass,jsRegexpGroup,@jsRegexpSpecial,@htmlPreproc oneline keepend
+syntax region  jsRegexpString     start=+\%(\%(\%(return\|case\)\s\+\)\@<=\|\%(\%([)\]"']\|\d\|\w\)\s*\)\@<!\)/\(\*\|/\)\@!+ skip=+\\.\|\[\%(\\.\|[^]]\)*\]+ end=+/[gimy]\{,4}+ contains=jsRegexpCharClass,jsRegexpGroup,@jsRegexpSpecial,@htmlPreproc oneline keepend
 syntax match   jsNumber           /\<-\=\d\+\(L\|[eE][+-]\=\d\+\)\=\>\|\<0[xX]\x\+\>/
 syntax keyword jsNumber           Infinity
 syntax match   jsFloat            /\<-\=\%(\d\+\.\d\+\|\d\+\.\|\.\d\+\)\%([eE][+-]\=\d\+\)\=\>/