[nikita.mmf]

var replace = (function (){
var ruleReplacable = {
  '<' : "&lt;",
  '>' : "&gt;",
  '"' : "&quot;"
};
return function ( text ) {
  return ("" + text).replace(/(<|>|")/g, function( match ){ return ruleReplacable[match] || match; })
};
})();
alert( replace('<div class="test">test</div>') );

И дальше по аналогии...