function checkForm() {
      for(i=0; i<document.forms[0].elements.length; i++)
      {
        if(document.forms[0].elements[i].type=="text" || document.forms[0].elements[i].type=="textarea")
        {
            str = document.forms[0].elements[i].value;
            str = str.replace(/&/g,"&amp;");
            str = str.replace(/</g,"&lt;");
            str = str.replace(/>/g,"&gt;");
            
            document.forms[0].elements[i].value = str;
        }

      }
  }