title: Add prefix for matches in string
body: <p>I have let's say this string: </p>
  
  <p><strong>"A = Beta * C / Delta + 2";</strong></p>
  
  <p>Now I want to replace all the variables(A, Beta, C, Delta) with the same name but with a prefix before it, like "x". So it would become:</p>
  
  <p><strong>"xA = xBeta * xC / xDelta + 2";</strong></p>
  
  <p>Maybe my head is just tired, but I can't think of a solution for this.</p>
  
  <p>To find matches, it's easy, just test against <strong>/[a-zA-Z]+/</strong> regex, but how in javascript should I get what I found and replace it easily not using multiple function calls?</p>