Comments on: Actionscript 3 Find and Replace String Performance Comparison

By: Tim McLeod

Tim McLeod — Tue, 22 Sep 2009 12:18:49 +0000

Cool, thanks!

By: mike chambers

mike chambers — Tue, 22 Sep 2009 07:36:52 +0000

fyi

This has been updated in the library:

http://code.google.com/p/as3corelib/issues/detail?id=87

thanks for the help…

mike chambers

By: Tim Herman

Tim Herman — Tue, 23 Jun 2009 21:20:58 +0000

You’re using quite a small string. I would try the replaces on much larger strings and see what kind of results you get. The two implementations may not have linear performance with respect to the length of the string.

By: Ryan Christiansen

Ryan Christiansen — Thu, 22 Jan 2009 18:52:31 +0000

As a follow up, it takes ~175ms to create the previous instance of RegExp 50,000 times. So if it were possible to reuse the same RegExp instance, it could be marginally faster than the split/join.

Both of the following declarations are identical.

// This is the shorthand form
var regExp:RegExp = /moon/g;

// This is the full class form
var regExp:RegExp = new RegExp(”moon”, “g”);

By: Ryan Christiansen

Ryan Christiansen — Thu, 22 Jan 2009 18:46:30 +0000

As a third comparison, I did some benchmarking of find/replace via regular expressions. You may have seen the native String method ‘replace()’:

myString.replace(pattern:*, repl:Object):String

This is an extremely powerful find and replace method allowing searches ignoring case, multiple group matches that can be used as parameters in the replace text, etc. (It’s all well documented in the Flash help).

In short i was able to do the same find and replace using regular expressions like this…

str.replace(/moon/g, “fence”);

The ‘g’ flag is important so that it replaces ALL matches of “moon” and not just the first one. You could also use the ‘i’ flag to perform a find/replace as case insensitive.

There are likely performance differences between our boxes, but here’s my results:

Split Join: ~475 ms
Regular Expressions: ~625 ms

I would consider that pretty small for the power that comes with it.

By: Tim McLeod

Tim McLeod — Thu, 22 Jan 2009 17:53:19 +0000

Will do. Thanks.

By: mike chambers

mike chambers — Thu, 22 Jan 2009 16:21:19 +0000

Thanks for doing the test. If you can log a bug with the issue (on the project page), then we can look at replacing the method with your code.

mike chambers

mesh@adobe.com