Question

With a string like “HorsieDoggieBirdie”, is there a non-capturing regex replace that would kill “Horsie” and “Birdie”, yet keep “Doggie” intact? I can only think of a capturing solution:

s/(Horsie)(Doggie)(Birdie)/$2/g

Is there a non-capturing solution like:

s/Horsie##Doggie##Birdie//g

where ## is some combination of regex codes? The specific problem is in JavaScript (innerHTML.replace) but I’ll take Perl suggestions, too.

Answer 1

You don’t have to capture the Horsie or the Birdie.

s/Horsie(Doggie)Birdie/$1/g;

A similar thing should work for Javascript as well. This is probably as efficient as it gets, and at least as fast as using look-around assertions; although you should benchmark it if you want to know for sure. (The results, of course, will depend on the horsies, doggies and birdies in question.)

Mandatory disclaimer: you should know what happens when you use regular expressions with HTML…