sorting - Javascript object array sort returns apparantly random results -

i trying simple sort working on object array seems returning random results. please have @ plunk: (in ff or chrome)

http://plnkr.co/edit/tqoyujv4nzvc4hakvrkz?p=preview

    var data;     var asc;      function init(){         data = [{username:"leonhaas"},{username:"0johnson"},{username:"leonlang"},{username:"0lechner"},{username:"0koller"},{username:"leonwinkler"},{username:"0schmidt"},{username:"0mueller"},{username:"0schmid"},{username:"lillyfuchs"},{username:"alexandragruber"},{username:"alexanderlechner"},{username:"alexanderpichler"},{username:"alexandraeder"},{username:"lillyreiter"},{username:"alibauer"},{username:"alexandrahall"},{username:"alexandrajohnson"},{username:"alexandrataylor"},{username:"alexandrawilliams"},{username:"lilywinkler"},{username:"alinabauer"},{username:"aliceegger"},{username:"alicesteiner"},{username:"alicewallner"},{username:"aliegger"},{username:"alifuchs"},{username:"linajohnson"},{username:"amarwhite"},{username:"alinaleitner"},{username:"alinaschmidt"},{username:"alinawood"},{username:"alischneider"}];         outputdata(data);         asc = true;     }      function sortit()     {         = data.username;         b = data.username;         if(asc){             data.sort(function(a,b)             {                 return 1;             });         } else {             data.sort(function(a,b)             {                 return -1;             });         }          outputdata(data);     }      function outputdata(data){         var output = "";         data.foreach(function (item){             output += item.username +"<br>";         });          var x=document.getelementbyid("demo");         x.innerhtml=output;     } 

in sorting function have compare data objects' usernames:

function sortit() {     if(asc){         data.sort(function(a,b)         {             return a.username.localecompare(b.username);         });     } else {         data.sort(function(a,b)         {             return b.username.localecompare(a.username);         });     }      outputdata(data); }