var xmlhttp;

function enviaContato(str)
{
xmlhttp=GetXmlHttpObject();

document.getElementById("bEnviar").style.display = "none";
document.getElementById("cloader").style.display = "block";

if (xmlhttp==null)
  {
  alert ("Browser does not support HTTP Request");
  return;
  }  
  /*inicia aqui*/
  var url = "envia_contato.php";
  //Variaveis aqui especificadas por ID
  if(document.getElementById("cnews").checked == true){
  var params = "nome=" + encodeURI(document.getElementById("nome").value )+
			   "&cemail=" + encodeURI(document.getElementById("cemail").value )+
			   "&telefone=" + encodeURI(document.getElementById("telefone").value )+
			   "&cidade="+ encodeURI(document.getElementById("cidade").value )+
			   "&msg=" + encodeURI(document.getElementById("msg").value ) +
			   "&cnews=" + encodeURI(document.getElementById("cnews").value );
  xmlhttp.open("POST", url, true);			   
  }else{
  var params = "nome=" + encodeURI(document.getElementById("nome").value )+
			   "&cemail=" + encodeURI(document.getElementById("cemail").value )+
			   "&telefone=" + encodeURI(document.getElementById("telefone").value )+
			   "&cidade="+ encodeURI(document.getElementById("cidade").value )+
			   "&msg=" + encodeURI(document.getElementById("msg").value );
  xmlhttp.open("POST", url, true);			   
  }	  
  //Send the proper header information along with the request
  xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
  xmlhttp.setRequestHeader("Content-length", params.length);
  xmlhttp.setRequestHeader("Connection", "close");
  
  xmlhttp.onreadystatechange = function() {//Call a function when the state changes.
	  if(xmlhttp.readyState == 4) {
		  //alert(xmlhttp.responseText);
		  //Resetando os valores padrões do formulario		  
		  document.getElementById("nome").value = 'Nome';
		  document.getElementById("cemail").value = 'E-mail';
		  document.getElementById("telefone").value = 'Telefone';
		  document.getElementById("cidade").value = 'Cidade';
		  document.getElementById("msg").value = 'Mensagem';
		  document.getElementById("cnews").checked = false;
		  document.getElementById("cloader").style.display="none";
		  document.getElementById("bOK").style.display = "block";
		  document.getElementById("bOK").disabled = "disabled";
	  }
  }
  xmlhttp.send(params);
  /*termina aqui*/
}

function GetXmlHttpObject()
{
if (window.XMLHttpRequest)
  {
  // code for IE7+, Firefox, Chrome, Opera, Safari
  return new XMLHttpRequest();
  }
if (window.ActiveXObject)
  {
  // code for IE6, IE5
  return new ActiveXObject("Microsoft.XMLHTTP");
  }
return null;
}