javascript - Javascripr LINQ: can't get SingleOrDefault to return a single value -

i using this library linq functionality in javascript. however, cannot singleordefault() work in code. returns multiple values.

here (angularjs) code:

customerservice.getcustomer(customerid)     .then(function (data) {         $scope.customer = data.data;         var primarycontact = enumerable.from(data.data.contacts)             .singleordefault(function (x) { return x.isprimarycontact });         if (primarycontact) $scope.customer.address = primarycontact.address.addresslines;         $scope.customer.customertype = 'default';     }) .catch(function (errordata) { alert("there has been error retrieving customer") }); 

the singleordefault() returns multiple values though know sure there 1 contact satisfies condition.

has used library , come across same problem? here sample of xml being consumed:

  <contacts>     <notification/>     <address>       <notification/>       <addressid>400059994</addressid>       <addresslines>my address       </addresslines>       <country>9000</country>       <county>east sussex</county>       <postcode>bn12 1pp</postcode>       <town>hove</town>     </address>     <contactid>400161871</contactid>     <emailaddress>myemail@test.com</emailaddress>     <isaccountscontact>false</isaccountscontact>     <isairlinelistcontact>false</isairlinelistcontact>     <isdefaultinvoicingcontact>false</isdefaultinvoicingcontact>     <isdeleted>false</isdeleted>     <ismarketingregistered>true</ismarketingregistered>     <isprimarybrokercontact>false</isprimarybrokercontact>     <isprimarycontact>true</isprimarycontact>     <telephonenumber>01273 123123</telephonenumber>     <website>www.fromthiscomesthat.co.uk</website>   </contacts>   <contacts>     <notification/>     <contactid>400161872</contactid>     <customercontacttype>15000</customercontacttype>     <forename>we</forename>     <isaccountscontact>false</isaccountscontact>     <isairlinelistcontact>false</isairlinelistcontact>     <isdefaultinvoicingcontact>false</isdefaultinvoicingcontact>     <isdeleted>false</isdeleted>     <ismarketingregistered>true</ismarketingregistered>     <isprimarybrokercontact>true</isprimarybrokercontact>     <isprimarycontact>false</isprimarycontact>     <surname>wew</surname>     <title>a test contract</title>   </contacts> 

i have found solution. changed 1 line add default value:

singleordefault(null, function (x) { return x.isprimarycontact }) 

i found documentation here, although feel little clearer.