How to search replace with regex and keep case as original in javascript

Question

Here is my problem. I have a string with mixed case in it. I want to search regardless of case and then replace the matches with some characters either side of the matches.

For example:

var s1 = "abC...ABc..aBC....abc...ABC";
var s2 = s.replace(/some clever regex for abc/g, "#"+original abc match+"#");

The result in s2 should end up like:

"#abC#...#ABc#..#aBC#....#abc#...#ABC#"

Can this be done with regex? If so, how?

Answer 1

This can be done using a callback function for regex replace.

var s1 = "abC...ABc..aBC....abc...ABC";

var s2 = s1.replace(/abc/ig, function (match) {
  return "#" + match + "#"  ;
}
 );

alert(s2);

demo : http://jsfiddle.net/dxeE9/