var xmlHttp

function obtenerSignature(preCode){ 
	xmlHttp=GetXmlHttpObject()
	if (xmlHttp==null)
	 {
		 alert ("Browser does not support HTTP Request")
		 return
	 }
	var url="getSignature.php"
	url=url+"?preCode="+preCode
	url=url+"&sid="+Math.random()
	xmlHttp.onreadystatechange=stateChanged 
	xmlHttp.open("GET",url,true)
	xmlHttp.send(null)
}

function stateChanged() { 
	if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete")
	 { 
	 document.getElementById("Ds_Merchant_MerchantSignature").value=xmlHttp.responseText.substring(0,40); 
	 } 
}

function GetXmlHttpObject(){
	var xmlHttp=null;
	try
	 {
		 // Firefox, Opera 8.0+, Safari
		 xmlHttp=new XMLHttpRequest();
	 }
	catch (e)
	 {
	 //Internet Explorer
		 try
		  {
			xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
		  }
		 catch (e)
		  {
			xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
		  }
	 }
	return xmlHttp;
}