function preg_quote (str, delimiter) {
  // http://kevin.vanzonneveld.net
  // +   original by: booeyOH
  // +   improved by: Ates Goral (http://magnetiq.com)
  // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  // +   bugfixed by: Onno Marsman
  // +   improved by: Brett Zamir (http://brett-zamir.me)
  // *     example 1: preg_quote("$40");
  // *     returns 1: '\$40'
  // *     example 2: preg_quote("*RRRING* Hello?");
  // *     returns 2: '\*RRRING\* Hello\?'
  // *     example 3: preg_quote("\\.+*?[^]$(){}=!<>|:");
  // *     returns 3: '\\\.\+\*\?\[\^\]\$\(\)\{\}\=\!\<\>\|\:'
  return (str + '').replace(new RegExp('[.\\\\+*?\\[\\^\\]$(){}=!<>|:\\' + (delimiter || '') + '-]', 'g'), '\\$&');
}

preg_quote("$40");

'\$40'

preg_quote("*RRRING* Hello?");

'\*RRRING\* Hello\?'

preg_quote("\\.+*?[^]$(){}=!<>|:");

'\\\.\+\*\?\[\^\]\$\(\)\{\}\=\!\<\>\|\:'