Array Null out side loop , but inside with values in Angular.js service

Question

Forgive me if this sounds like a dumb question/awkward wording, So my service function as follows, i have a array variable outside the function

    var newUsdToForeignRates = [];

then fucntion as follows,

function refresh() {
for(var i =0;i<shortArrays.length;i++){
  var url = YAHOO_FINANCE_URL_PATTERN.
  replace('PAIRS', 'USD' + shortArrays[i].join('","USD'));

   //ajax call to yql query
   $http.jsonp(url).success(function(data) {
    if(data.query.results.rate){
     angular.forEach(data.query.results.rate, function(rate) {
         var currency = rate.id.substring(3,6);
         newUsdToForeignRates.push(rate);

         //Array with all values :- working fine
         console.log(newUsdToForeignRates);
         // result [object,object,....etc];
     });
    }
   });
}

// this always null
console.log(newUsdToForeignRates);
// result  []  -- null
return newUsdToForeignRates;
}

thanks in advance

UPDATED

---

here is the full code..

angular.module('exchangeRate',[]).factory('serviceobject',['$http',function($http){
var YAHOO_FINANCE_URL_PATTERN =
      'http://query.yahooapis.com/v1/public/yql?q=select * from '+
      'yahoo.finance.xchange where pair in ("PAIRS")&format=json&'+
      'env=store://datatables.org/alltableswithkeys&callback=JSON_CALLBACK';
var currencieNames =new Array();
var newUsdToForeignRates = [];
var currencies = [
     {"id":"AED","name":"United Arab Emirates Dirham (AED)"},
     {"id":"AFN","name":"Afghan Afghani (AFN)"},
     {"id":"ALL","name":"Albanian Lek (ALL)"},
     {"id":"AMD","name":"Armenian Dram (AMD)"},{"id":"ANG","name":"Netherlands               Antillean"},{"id":"AOA","name":"Angolan Kwanza (AOA)"},{"id":"ARS","name":"Argentine Peso (ARS)"},{"id":"AUD","name":"Australian Dollar (A$)"},{"id":"AWG","name":"Aruban Florin (AWG)"},{"id":"AZN","name":"Azerbaijani Manat (AZN)"},{"id":"BAM","name":"Bosnia-Herzegovina Convertible Mark (BAM)"},{"id":"BBD","name":"Barbadian Dollar (BBD)"},{"id":"BDT","name":"Bangladeshi Taka (BDT)"},{"id":"BGN","name":"Bulgarian Lev (BGN)"},{"id":"BHD","name":"Bahraini Dinar (BHD)"},{"id":"BIF","name":"Burundian Franc (BIF)"},{"id":"BMD","name":"Bermudan Dollar (BMD)"},{"id":"BND","name":"Brunei Dollar (BND)"},{"id":"BOB","name":"Bolivian Boliviano (BOB)"},{"id":"BRL","name":"Brazilian Real (R$)"},{"id":"BSD","name":"Bahamian Dollar (BSD)"},{"id":"BTN","name":"Bhutanese Ngultrum (BTN)"},{"id":"BWP","name":"Botswanan Pula (BWP)"},{"id":"BYR","name":"Belarusian Ruble (BYR)"},{"id":"BZD","name":"Belize Dollar (BZD)"},{"id":"CAD","name":"Canadian Dollar (CA$)"},{"id":"CDF","name":"Congolese Franc (CDF)"},{"id":"CHF","name":"Swiss Franc (CHF)"},{"id":"CLF","name":"Chilean Unit of Account (UF) (CLF)"},{"id":"CLP","name":"Chilean Peso (CLP)"},{"id":"CNH","name":"CNH (CNH)"},{"id":"CNY","name":"Chinese Yuan (CN¥)"},{"id":"COP","name":"Colombian Peso (COP)"},{"id":"CRC","name":"Costa Rican Colón (CRC)"},{"id":"CUP","name":"Cuban Peso (CUP)"},{"id":"CVE","name":"Cape Verdean Escudo (CVE)"},{"id":"CZK","name":"Czech Republic Koruna (CZK)"},{"id":"DEM","name":"German Mark (DEM)"},{"id":"DJF","name":"Djiboutian Franc (DJF)"},{"id":"DKK","name":"Danish Krone (DKK)"},{"id":"DOP","name":"Dominican Peso (DOP)"},{"id":"DZD","name":"Algerian Dinar (DZD)"},{"id":"EGP","name":"Egyptian Pound (EGP)"},{"id":"ERN","name":"Eritrean Nakfa (ERN)"},{"id":"ETB","name":"Ethiopian Birr (ETB)"},{"id":"EUR","name":"Euro (€)"},{"id":"FIM","name":"Finnish Markka (FIM)"},{"id":"FJD","name":"Fijian Dollar (FJD)"},{"id":"FKP","name":"Falkland Islands Pound (FKP)"},{"id":"FRF","name":"French Franc (FRF)"},{"id":"GBP","name":"British Pound Sterling (£)"},{"id":"GEL","name":"Georgian Lari (GEL)"},{"id":"GHS","name":"Ghanaian Cedi (GHS)"},{"id":"GIP","name":"Gibraltar Pound (GIP)"},{"id":"GMD","name":"Gambian Dalasi (GMD)"},{"id":"GNF","name":"Guinean Franc (GNF)"},{"id":"GTQ","name":"Guatemalan Quetzal (GTQ)"},{"id":"GYD","name":"Guyanaese Dollar (GYD)"},{"id":"HKD","name":"Hong Kong Dollar (HK$)"},{"id":"HNL","name":"Honduran Lempira (HNL)"},{"id":"HRK","name":"Croatian Kuna (HRK)"},{"id":"HTG","name":"Haitian Gourde (HTG)"},{"id":"HUF","name":"Hungarian Forint (HUF)"},{"id":"IDR","name":"Indonesian Rupiah (IDR)"},{"id":"IEP","name":"Irish Pound (IEP)"},{"id":"ILS","name":"Israeli New Sheqel"},{"id":"INR","name":"Indian Rupee (Rs.)"},{"id":"IQD","name":"Iraqi Dinar (IQD)"},{"id":"IRR","name":"Iranian Rial (IRR)"},{"id":"ISK","name":"Icelandic Króna (ISK)"},{"id":"JMD","name":"Jamaican Dollar (JMD)"},{"id":"JOD","name":"Jordanian Dinar (JOD)"},{"id":"JPY","name":"Japanese Yen (¥)"},{"id":"KES","name":"enyan Shilling (KES)"},{"id":"KGS","name":"Kyrgystani Som (KGS)"},{"id":"KHR","name":"Cambodian Riel (KHR)"},{"id":"KMF","name":"Comorian Franc (KMF)"},{"id":"KPW","name":"North Korean Won (KPW)"},{"id":"KRW","name":"South Korean Won (?)"},{"id":"KWD","name":"Kuwaiti Dinar (KWD)"},{"id":"KYD","name":"Cayman Islands Dollar (KYD)"},{"id":"KZT","name":"Kazakhstani Tenge (KZT)"},{"id":"LAK","name":"Laotian Kip (LAK)"},{"id":"LBP","name":"Lebanese Pound (LBP)"},{"id":"LKR","name":"Sri Lankan Rupee (LKR)"},{"id":"LRD","name":"Liberian Dollar (LRD)"},{"id":"LSL","name":"Lesotho Loti (LSL)"},{"id":"LTL","name":"Lithuanian Litas (LTL)"},{"id":"LVL","name":"Latvian Lats (LVL)"},{"id":"LYD","name":"Libyan Dinar (LYD)"},{"id":"MAD","name":"Moroccan Dirham (MAD)"},{"id":"MDL","name":"Moldovan Leu (MDL)"},{"id":"MGA","name":"Malagasy Ariary (MGA)"},{"id":"MKD","name":"Macedonian Denar (MKD)"},{"id":"MMK","name":"Myanma Kyat (MMK)"},{"id":"MNT","name":"Mongolian Tugrik (MNT)"},{"id":"MOP","name":"Macanese Pataca (MOP)"},{"id":"MRO","name":"Mauritanian Ouguiya (MRO)"},{"id":"MUR","name":"Mauritian Rupee (MUR)"},{"id":"MVR","name":"Maldivian Rufiyaa (MVR)"},{"id":"MWK","name":"Malawian Kwacha (MWK)"},{"id":"MXN","name":"Mexican Peso (MX$)"},{"id":"MYR","name":"Malaysian Ringgit (MYR)"},{"id":"MZN","name":"Mozambican Metical (MZN)"},{"id":"NAD","name":"Namibian Dollar (NAD)"},{"id":"NGN","name":"Nigerian Naira (NGN)"},{"id":"NIO","name":"Nicaraguan Córdoba (NIO)"},{"id":"NOK","name":"Norwegian Krone (NOK)"},{"id":"NPR","name":"Nepalese Rupee (NPR)"},{"id":"NZD","name":"New Zealand Dollar (NZ$)"},{"id":"OMR","name":"Omani Rial (OMR)"},{"id":"PAB","name":"Panamanian Balboa (PAB)"},{"id":"PEN","name":"Peruvian Nuevo Sol (PEN)"},{"id":"PGK","name":"Papua New Guinean Kina (PGK)"},{"id":"PHP","name":"Philippine Peso (Php)"},{"id":"PKG","name":"PKG (PKG)"},{"id":"PKR","name":"Pakistani Rupee (PKR)"},{"id":"PLN","name":"Polish Zloty (PLN)"},{"id":"PYG","name":"Paraguayan Guarani (PYG)"},{"id":"QAR","name":"Qatari Rial (QAR)"},{"id":"RON","name":"Romanian Leu (RON)"},{"id":"RSD","name":"Serbian Dinar (RSD)"},{"id":"RUB","name":"Russian Ruble (RUB)"},{"id":"RWF","name":"Rwandan Franc (RWF)"},{"id":"SAR","name":"Saudi Riyal (SAR)"},{"id":"SBD","name":"Solomon Islands Dollar (SBD)"},{"id":"SCR","name":"Seychellois Rupee (SCR)"},{"id":"SDG","name":"Sudanese Pound (SDG)"},{"id":"SEK","name":"Swedish Krona (SEK)"},{"id":"SGD","name":"Singapore Dollar (SGD)"},{"id":"SHP","name":"Saint Helena Pound (SHP)"},{"id":"SLL","name":"Sierra Leonean Leone (SLL)"},{"id":"SOS","name":"Somali Shilling (SOS)"},{"id":"SRD","name":"Surinamese Dollar (SRD)"},{"id":"STD","name":"Sao Tomé and Príncipe Dobra (STD)"},{"id":"SVS","name":"alvadoran Colón (SVC)"},{"id":"SYP","name":"Syrian Pound (SYP)"},{"id":"SZL","name":"Swazi Lilangeni (SZL)"},{"id":"THB","name":"Thai Baht (?)"},{"id":"TJS","name":"Tajikistani Somoni (TJS)"},{"id":"TMT","name":"Turkmenistani Manat (TMT)"},{"id":"TND","name":"Tunisian Dinar (TND)"},{"id":"TOP","name":"Tongan Pa?anga (TOP)"},{"id":"TRY","name":"Turkish Lira (TRY)"},{"id":"TTD","name":"Trinidad and Tobago Dollar (TTD)"},{"id":"TWD","name":"New Taiwan Dollar (NT$)"},{"id":"TZS","name":"Tanzanian Shilling (TZS)"},{"id":"UAH","name":"Ukrainian Hryvnia (UAH)"},{"id":"UGX","name":"Ugandan Shilling (UGX)"},{"id":"USD","name":"US Dollar ($)"},{"id":"UYU","name":"Uruguayan Peso (UYU)"},{"id":"UZS","name":"Uzbekistan Som (UZS)"},{"id":"VEF","name":"Venezuelan Bolívar (VEF)"},{"id":"VND","name":"Vietnamese Dong (?)"},{"id":"VUV","name":"Vanuatu Vatu (VUV)"},{"id":"WST","name":"Samoan Tala (WST)"},{"id":"XAF","name":"CFA Franc BEAC (FCFA)"},{"id":"XCD","name":"East Caribbean Dollar (EC$)"},{"id":"XDR","name":"Special Drawing Rights (XDR)"},{"id":"XOF","name":"CFA Franc BCEAO (CFA)"},{"id":"XPF","name":"CFP Franc (CFPF)"},{"id":"YER","name":"Yemeni Rial (YER)"},{"id":"ZAR","name":"South African Rand (ZAR)"},{"id":"ZMK","name":"Zambian Kwacha (1968-2012) (ZMK)"},{"id":"ZMW","name":"Zambian Kwacha (ZMW)"},{"id":"ZWL","name":"Zimbabwean Dollar (2009) (ZWL)"}
   ];
for(var i=0;i<currencies.length;i++){
    currencieNames.push(currencies[i]["id"]); 
} 

var shortArrays = [], i, len;
for (i = 0, len = currencieNames.length; i < len; i += 50) {
    shortArrays.push(currencieNames.slice(i, i + 50));
}

return {
    currencies: currencieNames,
    refresh: refresh(),
 };

function refresh() {
for(var i =0;i<shortArrays.length;i++){
  var url = YAHOO_FINANCE_URL_PATTERN.
  replace('PAIRS', 'USD' + shortArrays[i].join('","USD'));
   $http.jsonp(url).success(function(data) {
    if(data.query.results.rate){
     angular.forEach(data.query.results.rate, function(rate) {
         var currency = rate.id.substring(3,6);
         newUsdToForeignRates.push(rate);
         //Array with all values :- working fine
         console.log(newUsdToForeignRates);
     });
    }
   });
}
// this always null
console.log(newUsdToForeignRates);
return newUsdToForeignRates;
}

}]);

and my call from controller as follows

 this.inCurr = serviceobject.refresh;
 console.log(this.inCurr);

Answer 1

The $http call is asynchronous, so you need to return a promise, then resolve the promise when the data is ready. Also, the global syntax for Angular is not good practice. Since you're doing ajax calls in a loop, you'll need to use $q.all for each promise and resolve the main promise when all the ajax calls are done (all the promises from the loop are done). Here's the basic logic for what you need to do. Live demo (click).

var app = angular.module('myApp', []);

app.controller('myCtrl', function(refresh) {
  //refresh() then use the data
  refresh().then(function(allData) {
    //this will run when all ajax calls are done - the refresh promise is resolved
    console.log(allData);
  });
});

app.factory('refresh', function ($q, $http) {

  var arr = [
    1,2,3,4
  ];

  //I made this into a function to avoid the loop incrementing "i"
  function makeCall(def) {
    //make the ajax call
    $http.get('my-file.json').then(function(resp) {
      //resolve this call's promise with the response data
      def.resolve(resp.data);
    });
  }

  return function() {
    //make a deferred for this function
    var deferred = $q.defer();

    //store all promises in one array for $q.all to use
    var allPromises = [];
    for (var i=0; i<arr.length; ++i) {
      //make a deferred for this call
      var def = $q.defer();
      //store the promise
      allPromises[i] = def.promise;
      makeCall(def);
    }

    //wait for all promises to resolve
    $q.all(allPromises).then(function(allData) {
      //then resolve the main promise
      //when this resolves, the "then" for "refresh()" will fire in the controller
      deferred.resolve(allData);
    })

    //return the main promise
    return deferred.promise;
  };
});

Answer 2

It is because $http methods (unless the request is cached) work asynchronously. So when you reach the console.log(newUsdToForeignRates) the result of HTTP call is not returned yet. If you need to handle the result you can $watch it and use or combine all of the queries into one promise by using $q.all ($q.all)