Replace text but keep case

Question

I have a set of strings that I need to replace, but I need to keep the case of letters.

Both the input words and output words are of the same length.

For example, if I need to replace "abcd" with "qwer", then the following should happen:

"AbcD" translates to "QweR" "abCd" translates to "qwEr" 

and so on.

Right now I'm using JavaScript's replace, but capital letters are lost on translation.

r = new RegExp( "(" + 'asdf' + ")" , 'gi' ); "oooAsdFoooo".replace(r, "qwer"); 

Any help would be appreciated.

Answer 1

Here’s a helper:

function matchCase(text, pattern) {     var result = '';      for(var i = 0; i < text.length; i++) {         var c = text.charAt(i);         var p = pattern.charCodeAt(i);          if(p >= 65 && p < 65 + 26) {             result += c.toUpperCase();         } else {             result += c.toLowerCase();         }     }      return result; } 

Then you can just:

"oooAsdFoooo".replace(r, function(match) {     return matchCase("qwer", match); });