AngularJS で Promise (defer)を使ってファイルシステムからファイルを読み込む (cordova filesystem) ref: http://qiita.com/mm36/items/a9869a2066ace1aed0a8

file0.txt

function slowCall() {
  var df = $q.defer();
  // 非同期処理を担当する関数を定義
  function fn() {
    var msg = 'now : ' + new Date().getTime();
    alert('inside async function.');
    df.resolve(msg);
  };
  $timeout(fn, 1000);
  return df.promise;
};

file1.txt

var testDeferSample = function () {
  alert('test defer sample start.');
  slowCall().then(function () {
    alert('END!');
  });
  alert('Opps.. outside');
};

file10.txt

var _writeFile = function(dirPath, fileName, fileText) {
  var deferred = $q.defer();
  getTargetDirectory(dirPath).then(function(dirEntry) {
    dirEntry.getFile(fileName, { create: true },
      function(fileEntry) {
        fileEntry.createWriter( 
          function(writer) {
            var cb = function() {
              //console.log("write end");
              alert("保存しました。");
              deferred.resolve(fileName);
            }
            writer.onwrite = cb;
            writer.onerror = function() { console.log("保存に失敗しました。"); }
            //console.log( fileText );
            writer.write( fileText );
          } ,
          function() {
            console.log("create writer error");
          }
        );
      },
      failFiles
    );
  });
  return deferred.promise;
};

file11.txt

var createJsonObject = function (targetDirPath, fileName) {
  var deferred = $q.defer();
  readFile(targetDirPath, fileName).then(function (content) {
    var json = { name: fileName, data: content };
    deferred.resolve(json);
  });
  return deferred.promise;
};

file12.txt

var createCallbackFunctionList = function (targetDirPath, fileNames) {
  var deferred = $q.defer();
  var functions = [];
  fileNames.map(function (fileName) {
    functions.push(createJsonObject(targetDirPath, fileName));
  });
  deferred.resolve(functions);
  return deferred.promise;
};

file13.txt

var getFileAsJsonList = function () {
  var jsonList = [];
  var targetDirPath = 'YOUR_TARGET/DIRECTORY/HERE';

  var deferred = $q.defer();
  // まずディレクトリにあるファイル名を元に、JSONオブジェクトを取ってくる関数を作る
  FileUtilService.listDir(targetDirPath).then(function (fileNames) {
    createCallbackFunctionList(targetDirPath, fileNames).then(function (fns) {
      deferred.resolve(fns);
    })
  });

  // ファイルコンテンツ取得時に非同期処理のため、ファイルの順序がバラバラになる
  // 全ファイルコンテンツの取得後に、ファイル名（日時）で並べ替え。
  deferred.promise.then(function (promises) {
    // 全部実行したい関数の配列を取得 then の後にくる関数は、
    // promisesが全て実行し終わったら一番最後に実行される
    $q.all(promises).then(function (photos) {
      jsonList = photos.sort(function (a, b) {
        return parseInt(b.name) - parseInt(a.name);
      });
      alert('got' + jsonList.length);
      angular.forEach(jsonList, function (value, key) {
        console.log('FileInfo : ' + value.name + ', content length=' + value.data.length);
      })
    });
  });
};

file2.txt

test defer sample start.
Opps.. outside
inside async function.
END!

file3.txt

var testAllSample = function() {
  alert('test sample start.');
  var p1 = slowCall().then(function(msg) {
    alert('LAST 1' + msg);
    return msg;
  });
  var p2 = slowCall().then(function(msg) {
    alert('LAST 2' + msg);
    return msg;
  });
  $q.all([p1,p2]).then(function(res) {
    alert('LAST MOST ' + res[0] + ', ' + res[1]);
  });
};

file4.txt

test all sample start.
inside async function.
LAST 1 1440643852941
inside async function.
LAST 2 1440643876515
LAST MOST 1440643852941, 1440643876515

file5.txt

var getFileSystem = function() {
  var deferred = $q.defer();
  window.requestFileSystem(window.PERSISTENT, 1024*1024, function(filesystem) {
    deferred.resolve(filesystem);
  });
  return deferred.promise;
};

file6.txt

var getTargetDirectory = function(dirPath) {
  var deferred = $q.defer();
  getFileSystem().then(function(filesystem) {
    filesystem.root.getDirectory(dirPath, { create: true, exclusive: false },
      function(dirEntry) {
        deferred.resolve(dirEntry);
      },
      failFiles
    );
  });
  return deferred.promise;
};

file7.txt

function failFiles(error) {
  alert('failFiles' + error.code);
};

file8.txt

var listDir = function (dirPath) {
  var deferred = $q.defer();
  getTargetDirectory(dirPath).then(function (dirEntry) {
    var reader = dirEntry.createReader();
    var fileNames = [];
    reader.readEntries(
      function (entries) {
        for (var i = 0; i < entries.length; i++) {
          fileNames.push(entries[i].name);
        }
        deferred.resolve(fileNames);
      },
      function (error) {
        console.log("reading target directory error");
      }
    );
  });
  return deferred.promise;
};

file9.txt

var readFile = function(dirPath, fileName) {
  var deferred = $q.defer();
  getTargetDirectory(dirPath).then(function(dirEntry) {
    dirEntry.getFile(fileName, { create: false },
      function(fileEntry) {
        fileEntry.file(function(file) {
          var reader = new FileReader();
          reader.onloadend = function() {
            deferred.resolve(this.result);
          };
          reader.readAsText(file);
        });
      },
      function(error) {
        console.log("reading target directory error");
      }
    );
  });
  return deferred.promise;
};