javascript - Cannot assign info from request properly Angular JS -

i need send few requests server , info write in array. function looks like:

   $scope.addinstrument = function(themat) {       $scope.data = '{"func":"addinstrument", "thematerial":"' + themat + '", ';       $scope.data += '"lifespan":"' + $scope.lifespan + '"}';         server.fetch($scope.data, $rootscope.token).then(function(data) {             return data[0].addinstrument;         })     } 

code in controller calls function:

for (var = 0; < $scope.amount; ++) {     $scope.inventnum[$scope.inventnum.length] = $scope.addinstrument(themat); } angular.foreach($scope.inventnum, function(value) {     alert(value); }) 

function sends requests server:

app.service('server', function (authservice) {   this.fetch = function (data, token) {     return fetch('http://104.197.58.108:8080', {           method: 'post',           headers: {             'accept': 'application/json',             'content-type': 'application/json'           },           body: json.stringify({               data: data,               token: token           })         })           .then(function(response) {              return response.json()           }).then(function(data) {             if (data.success == false) {               return authservice.logout();             } else {               return data;             }           })   } }) 

after that, alerts 'undefined' right amount of times. tried assign values array in function addinstrument():

   $scope.addinstrument = function(themat) {       $scope.data = '{"func":"addinstrument", "thematerial":"' + themat + '", ';       $scope.data += '"lifespan":"' + $scope.lifespan + '"}';         server.fetch($scope.data, $rootscope.token).then(function(data) {             $scope.inventnum[$scope.inventnum.length] = data[0].addinstrument;         })     } 

but in case there mistakes cannot read property length of undefined.