JavaScript regex refactoring

Question

I'm performing this on a string:

var poo = poo
.replace(/[%][<]/g, "'<")
.replace(/[>][%]/g, ">'")
.replace(/[%]\s*[+]/g, "'+")
.replace(/[+]\s*[%]/g, "+'");

Given the similar if these statements, can these regexs be comebined somehow?

Answer 1

No, I don't think so. At least, I suspect for any transformation involving fewer replaces I can come up with a string that your original and the proposed alternative treat differently. However, it may be that the text you're working with wouldn't trigger the differences, and so for practical purposes a shorter transformation would work as well. Depends on the text.

Answer 2

You can simplify it a little bit. You don't need all the range syntax

poo
.replace(/%</g, "'<")
.replace(/>%/g, ">'")
.replace(/%\s*\+/g, "'+")
.replace(/\+\s*%/g, "+'");

Answer 3

Since in either case, the replacement only turns % into ' and removes spaces:

var poo = 'some annoying %< string >% with some %  + text  +   %';

poo = poo.replace(/%<|>%|%\s*\+|\+\s*%/g, function(match) { 
  return match.replace('%', '\'').replace(/\s/g,''); 
});

// "some annoying '< string >' with some ' + text + '"

Although that's not much simpler...

Answer 4

Using lookahead assertions and capturing:

var poo = poo.replace(/%(?=<)|(>)%|%\s*(?=\+)|(\+)\s*%/g, "$1$2'");

Using capturing alone:

var poo = poo.replace(/(>)%|(\+)\s*%|%(<)|%\s*(\+)/g, "$1$2'$3$4");

If JS's RegExp supported lookbehind assertions:

var poo = poo.replace(/%(?=<)|(?<=>)%|%\s*(?=\+)|(?<=\+)\s*%/g, "'");

but it doesn't.