Javascript Replace All with Case Insensitive Matching

Introduction

I was using the regex replace all, but found out it had errors replacing certain reserved characters without escaping them first. So I wrote a custom method, it seems to work pretty well. Please, help test with internet explorer and windows. Also, please let me know if I have goofed with string pointer positions. I haven't fully tested it yet, but I hope it is flawless. Thanks!

Please speed test it here.
http://jsperf.com/javascript-replace-all/8[^]
http://jsperf.com/javascript-replace-all/10[^]

JavaScript - Prototype Version

// Find, Replace, Case
String.prototype.replaceAll = function(_f, _r, _c){ 

  var o = this.toString();
  var r = '';
  var s = o;
  var b = 0;
  var e = -1;
  if(_c){ _f = _f.toLowerCase(); s = o.toLowerCase(); }

  while((e=s.indexOf(_f)) > -1)
  {
    r += o.substring(b, b+e) + _r;
    s = s.substring(e+_f.length, s.length);
    b += e+_f.length;
  }

  // Add Leftover
  if(s.length>0){ r+=o.substring(o.length-s.length, o.length); }

  // Return New String
  return r;
};
//

// Replaces Case Matching - Param = FindString, ReplaceString, ICaseBoolean 
'Test to see if this works? (Yes|No)'.replaceAll('(Yes|No)', 'Yes!');

// Replaces Case Insensitive Matching with True
'Test to see if this works? (Yes|No)'.replaceAll('(yes|no)', 'Yes!', true);

JavaScript - Direct Function Version

function replaceAll(_s, _f, _r, _c){ 

  var o = _s.toString();
  var r = '';
  var s = o;
  var b = 0;
  var e = -1;
  if(_c){ _f = _f.toLowerCase(); s = o.toLowerCase(); }

  while((e=s.indexOf(_f)) > -1)
  {
    r += o.substring(b, b+e) + _r;
    s = s.substring(e+_f.length, s.length);
    b += e+_f.length;
  }

  // Add Leftover
  if(s.length>0){ r+=o.substring(o.length-s.length, o.length); }

  // Return New String
  return r;
}

// Replaces Case Matching - Results = replaceAll(FindString, ReplaceString, ICaseBoolean) 
replaceAll('Test to see if this works? (Yes|No)', '(Yes|No)', 'Yes!');

// Replaces Case Insensitive Matching with True
replaceAll('Test to see if this works? (Yes|No)', '(yes|no)', 'Yes!', true);

PHP - Direct Function Version

function replaceAll($_s, $_f, $_r, $_c=false)
{ 
  $o = $_s;
  $r = '';
  $s = $o;
  $b = 0;
  $e = -1;
  if($_c){ $_f = strtolower($_f); $s = strtolower($o); }

  while(($e=strpos($s, $_f))!=false)
  {
    $r .= substr($o, $b, ($b + $e)) . $_r;
    $s = substr($s, ($e + strlen($_f)), strlen($s));
    $b += $e + strlen($_f);
  }

  // Add Leftover
  if(strlen($s)>0){ $r.=substr($o, (strlen($o) - strlen($s)), strlen($o)); }

  // Return New String
  return $r;
}

// Replaces Case Matching - Results = replaceAll(FindString, ReplaceString, ICaseBoolean) 
replaceAll('Test to see if this works? (Yes|No)', '(Yes|No)', 'Yes!');

// Replaces Case Insensitive Matching with True
replaceAll('Test to see if this works? (Yes|No)', '(yes|no)', 'Yes!', true);

Javascript - Prototype REGEX Version

/* DO NOT USE - Regex has issues replacing reserved characters unless they are escaped. Found out the hard way! */
String.prototype.replaceAll = function()
{ 
  return this.toString().replace(new RegExp(arguments[0], 'g' +
 ((arguments[2])? 'i': '') ), arguments[1]); 
};