updating field/Attribute using crmservice in java script

Here is the process to update field using crmservice

var xml1 = "<?xml version='1.0' encoding='utf-8'?>"+

"<soap:Envelope xmlns:soap='http://schemas.xmlsoap.org/soap/envelope/'"+

" xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'"+

" xmlns:xsd='http://www.w3.org/2001/XMLSchema'>"+

GenerateAuthenticationHeader()+

"<soap:Body>"+

"<Update xmlns='http://schemas.microsoft.com/crm/2007/WebServices'>"+

"<entity xsi:type='new_entity'>" +

"<new_field1>"+ xmlencode(data) +"</new_field1>" +

"<new_primarykeyfield>" + crmForm.ObjectId + "</new_primarykeyfield>" +

"</entity>"+

"</Update>"+

"</soap:Body>"+

"</soap:Envelope>";

var xHReq1 = new ActiveXObject("Msxml2.XMLHTTP");

xHReq1.Open("POST", "/mscrmservices/2007/CrmService.asmx", false);

xHReq1.setRequestHeader("SOAPAction","http://schemas.microsoft.com/crm/2007/WebServices/Update");

xHReq1.setRequestHeader("Content-Type", "text/xml; charset=utf-8");

xHReq1.setRequestHeader("Content-Length", xml1.length);

xHReq1.send(xml1);

// Capture the result

var resultXml1 = xHReq1.responseXML;

var errorCount1 = resultXml1.selectNodes('//error').length;

//  Encoding method to replace special characters of the field data

function xmlencode(string) {

    return string.replace(/\&/g,'&'+'amp;').replace(/</g,'&'+'lt;').replace(/>/g,'&'+'gt;').replace(/\'/g,'&'+'apos;').replace(/\"/g,'&'+'quot;');

}