Angular - [].concat.apply return empty array

Question

I have this Ionic code:

.factory('resultsFactory', function($http, $q, $rootScope, $firebaseArray, $timeout) { 
  var results = {};  

  function _all(){
    var d = $q.defer();
    var palabras =  $rootScope.textAreaOfrecer.toLowerCase().split(' ');
    var solicitudes = [];
    Promise.all(
              solicitudes = palabras.map(palabra => $firebaseArray(firebase.database().ref().child("solCompras").orderByChild("palabras/" 
                                               + palabra).equalTo(true) ) )
                     );

    var array = [].concat.apply([],solicitudes);

    d.resolve(array);

    return d.promise;       
  }

  results.all = _all;
  return results;
})

The problem is that the code: var array = [].concat.apply([],solicitudes); return an empty array.

Hi. What output are you expecting? Please post more details so that we can assist you with your problem. — BusyProgrammer, Feb 23 '17 at 02:22

score 0 · Answer 1 · edited Feb 23 '17 at 04:58

0

Using [].concat.apply(solicitudes) instead. It may be that palabras is an empty array, then [].map(...) == [] can return Promise.all(solicitudes) directly.

function _all() {
        var palabras = $rootScope.textAreaOfrecer.toLowerCase().split(' ');
        return Promise.all(palabras.map((palabra) => {
            return $firebaseArray(firebase.database().ref().child("solCompras").orderByChild("palabras/" + palabra).equalTo(true));
        }));
    }

edited Feb 23 '17 at 04:58

mbigras

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answered Feb 23 '17 at 01:52

holi-java

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sorry i didnt understand – Ariel Brizi Feb 23 '17 at 01:58
check the collection `palabras` whether is an empty array? if true then palabras.map(...) always return [] – holi-java Feb 23 '17 at 02:01
debug map/concat function whether always return []? – holi-java Feb 23 '17 at 02:06
in fact this is not the problem. "array = [].concat.apply([],solicitudes);" array is what always keep in null. but "solicitudes" have elements. its an array of arrays that i want to unify – Ariel Brizi Feb 23 '17 at 02:15
the code "array = [].concat.apply([],solicitudes);" no problem.if `solicitudes` have elements & array is null then the `[].concat.apply([],solicitudes)` concat/apply function may be changed by someone.you can use `var strings=[].concat.apply([],['foo','bar']);console.log(strings);`before `array` assignment and see the result. – holi-java Feb 23 '17 at 02:25
In fact,you can use [].concat([]) directly because `palabras` is an array,using concat.apply is redundant. – holi-java Feb 23 '17 at 02:30

score 0 · Answer 2 · answered Feb 24 '17 at 01:29

$scope.solicitudes = [{post: 'Loading..'}];


Promise.all(
      $scope.solicitudes = palabras.map(palabra => $firebaseArray(firebase.database().ref().child("solCompras").orderByChild("palabras/" + palabra
                                                   ).equalTo(true) ) )
             ).then( function (){
                               //http://www.jstips.co/en/flattening-multidimensional-arrays-in-javascript/
                               var myNewArray = $scope.solicitudes.reduce(function(prev, curr) {
                                 return prev.concat(curr);
                               });

                               $scope.solicitudes = myNewArray;
                         });

Angular - [].concat.apply return empty array

2 Answers2