Status: New
Owner: ----
Labels: Type-Defect Priority-Medium Performance
New issue 1337 by [email protected]: constant regexps are always
re-constructed every time they're used
http://code.google.com/p/google-caja/issues/detail?id=1337
when js uses a constant regexp like
s = s.replace(/\s+/, '');
the es53 rewriter turns it into something like this:
s = (x0___ = new RegExp.new___('\\s+'), s.replace_m___?
s.replace(x0___, 'x'): s.m___('replace', [ x0___, 'x' ]
which means a new RegExp object is constructed every time that code is
executed.
RegExp construction is kind of expensive, not just the parse time of the
RegExp. each RegExp construction calls DefineOwnProperty___ five times,
and DefineOwnProperty___ is kind of expensive.
(this is one of of the reasons the markdown example is sluggish when
cajoled.)
