getjson - jQuery JSON parse: undefined object -

i have used jquery's getjson() data server. response looks me. how looks

{"user" :[{"username":"nupac"},{"username":"nupac2"}]} 

when alert(objects.keys(jsonresponse)); user in alert box fine when try access data jsonresponse['user'] undefined.

why getting undefined? think should array of objects.

edit:

here code real url,

 function getlmslinks(email){         $.getjson("url?student=" + email, function(d) {             alert(object.keys(d));             alert(d['user']);          }).fail( function(d, textstatus, error) {             //alert("fail " + textstatus + " error " + error);              console.error("getjson failed, status: " + textstatus + ", error: "+error)         });       } 

are looking this

 var jsonresponse = { "user": [{ "username": "nupac" }, { "username": "nupac2"}] }      alert(jsonresponse.user[0].username); 

if string, first need make object using

 jsonresponse =jquery.parsejson(jsonresponse); 

then can use like

alert(jsonresponse.user[0].username); 

edit

 $.getjson("http://prinyautils.appspot.com/getlmsurl?student=" + email, function(d) {         alert(object.keys(d));         alert(d.user[0].username);      }).fail( function(d, textstatus, error) {         //alert("fail " + textstatus + " error " + error);          console.error("getjson failed, status: " + textstatus + ", error: "+error)     });