Attempting to parse data from XML response

Question

From a website web page. there's an input text field (policynum) and a call button (policynum). I created a function (getEntity) that renders an XML response. From the XML response, the goal is to parse out data from tag . I created a second function (getEntity1), but the button doesn't respond. Note: I remember to change onclick function name.; see code below:

<input id="policynum" name="policynum" type="text" value="">
<button id="policynum" class="btnSize" onclick="getEntity()">GET ENTITY ID</button>

function getEntity() {
    location.href='https://chwebsrvr.blserviceinc.com/ETM/admin/setup/context/ConceptOne/'+ document.getElementById('policynum').value+'/ConceptOne';
}

XML Response below with tag data

<ContextGet Reply_Code="1" Process_Status="PRC" Process_Message="Transaction 
       successfully processed." View="full">
   <Context System_Code="ConceptOne" Login_Name="CICFL000003-00" 
       App_Code="ConceptOne">
      <Context_Name>ETM Policy Holder</Context_Name>
      <Context_Config>
        <![CDATA[
          <ConceptOne> 
              <Entity_ID>86100</Entity_ID> 
              <Role_Type>CN</Role_Type> 
              <Team_Role>AGTBND</Team_Role> 
          </ConceptOne>
         ]]>
       </Context_Config>
    </Context>
</ContextGet>

This function will replace geetEntity function to return data to the screen from Entity_ID tag:

function getEntity1() {
    XmlDocument xml = new XmlDocument();
    xml.LoadXml(myXmlString);
    XmlNodeList xnList = xml.SelectNodes("//ConceptOne");
    foreach (XmlNode xn in xnList)
    {
        XmlNode example = null;
        string na = "";
        example = xn.SelectSingleNode("Entity_ID");
        if (example != null)
        {
            na = example.InnerText;
        }
    }
  $response = $client->request('GET', 
  'https://chwebsrvr.blserviceinc.com/ETM/admin/setup/context/ConceptOne/'+ 
  document.getElementById('policynum').value+'/ConceptOne');
  $response = $response->getBody()->getContents();
}

Suggestion please...