title: replacement of string using regular expression at Xth position intervals (javascript)
body: <p>I would very much appreciate some assistance from the community on replacing a string at xth position intervals, using javascript regex.  For example, if the string length is 161 and the replacement text is <code>&lt;br /&gt;</code>, regex would replace the string at the 40th, 80th, 120th, and 160th positions with this replacement text.  Is this possible using regex?</p>
  
  <p>Thank you very much.</p>