Dynamics 365:How to filter lookup control based on another lookup value using JavaScript

Ex:Display only the contacts that belong to selected account.

//when account lookup value changed

function onAccountChanged() {

    var AccountId = getLookupValue("customerid");

    if (AccountId != null) {

        Xrm.Page.getControl("contactid").removePreSearch(function () {

            addLookupFilter();

        });

        Xrm.Page.getControl("contactid").addPreSearch(function () {

            addLookupFilter();

        });

        Xrm.Page.getAttribute("contactid").setValue(null);

    }

    else {

        Xrm.Page.getControl("contactid").removePreSearch(function () {

            addLookupFilter();

        });

        Xrm.Page.getAttribute("contactid").setValue(null);

    }

}

function addLookupFilter() { 

    var accountId = getLookupValue("customerid"); 

    var fetchXml = "<filter type='and'><condition value='" + accountId + "' attribute='parentcustomerid' uitype='account'  operator='eq' /></filter>";

    Xrm.Page.getControl("alfa_address").addCustomFilter(fetchXml);

}

 //***************************

function getLookupValue(fieldname) {

    var lookupObj = Xrm.Page.getAttribute(fieldname);

    if (lookupObj.getValue() != null)

        return lookupObj.getValue()[0].id;

    else

        return null;

};