Simple File API wrapper using Q.js. Same code as in http://github.com/photokandyStudios/YASMF-Next/blob/master/lib/yasmf/util/fileManager.js, except wrapped in a global function. The code below will add a FileManager object to `window`, if it is passed in (otherwise it will only return it). It can then be used as seen in this demo: http://jsbin.…

FileManager.js

;(
function( Q, BaseObject, globalContext ) {
    /**
     * Defined by Q, actually, but defined here to make type handling nicer
     * @typedef {{}} Promise
     */
    var DEBUG = false;
    /**
     * Requests a quota from the file system
     * @method _requestQuota
     * @private
     * @param  {*} fileSystemType    PERSISTENT or TEMPORARY
     * @param  {Number} requestedDataSize The quota we're asking for
     * @return {Promise}                   The promise
     */
    function _requestQuota( fileSystemType, requestedDataSize ) {
      var deferred = Q.defer();
      if ( DEBUG ) {
        console.log( [ "_requestQuota: ", fileSystemType, requestedDataSize ].join(
          " " ) )
      }
      try {
        // attempt to ask for a quota
        var PERSISTENT = ( typeof LocalFileSystem !== "undefined" ) ?
          LocalFileSystem.PERSISTENT : window.PERSISTENT;
        // Chrome has `webkitPersistentStorage` and `navigator.webkitTemporaryStorage`
        var storageInfo = fileSystemType == PERSISTENT ? navigator.webkitPersistentStorage :
          navigator.webkitTemporaryStorage;
        if ( storageInfo ) {
          // now make sure we can request a quota
          if ( storageInfo.requestQuota ) {
            // request the quota
            storageInfo.requestQuota( requestedDataSize, function success(
              grantedBytes ) {
              if ( DEBUG ) {
                console.log( [ "_requestQuota: quota granted: ", fileSystemType,
                  grantedBytes
                ].join( " " ) )
              }
              deferred.resolve( grantedBytes );
            }, function failure( anError ) {
              if ( DEBUG ) {
                console.log( [ "_requestQuota: quota rejected: ", fileSystemType,
                  requestedDataSize, anError
                ].join( " " ) )
              }
              deferred.reject( anError );
            } );
          } else {
            // not everything supports asking for a quota -- like Cordova.
            // Instead, let's assume we get permission
            if ( DEBUG ) {
              console.log( [
                "_requestQuota: couldn't request quota -- no requestQuota: ",
                fileSystemType, requestedDataSize
              ].join( " " ) )
            }
            deferred.resolve( requestedDataSize );
          }
        } else {
          if ( DEBUG ) {
            console.log( [
              "_requestQuota: couldn't request quota -- no storageInfo: ",
              fileSystemType, requestedDataSize
            ].join( " " ) )
          }
          deferred.resolve( requestedDataSize );
        }
      } catch ( anError ) {
        deferred.reject( anError );
      }
      return deferred.promise;
    }
    /**
     * Request a file system with the requested size (obtained first by getting a quota)
     * @method _requestFileSystem
     * @private
     * @param  {*} fileSystemType    TEMPORARY or PERSISTENT
     * @param  {Number} requestedDataSize The quota
     * @return {Promise}                   The promise
     */
    function _requestFileSystem( fileSystemType, requestedDataSize ) {
      var deferred = Q.defer();
      if ( DEBUG ) {
        console.log( [ "_requestFileSystem: ", fileSystemType, requestedDataSize ].join(
          " " ) )
      }
      try {
        // fix issue #2 by chasen where using `webkitRequestFileSystem` was having problems
        // on Android 4.2.2
        var requestFileSystem = window.requestFileSystem || window.webkitRequestFileSystem;
        requestFileSystem( fileSystemType, requestedDataSize, function success(
          theFileSystem ) {
          if ( DEBUG ) {
            console.log( [ "_requestFileSystem: got a file system", theFileSystem ]
              .join( " " ) )
          }
          deferred.resolve( theFileSystem );
        }, function failure( anError ) {
          if ( DEBUG ) {
            console.log( [ "_requestFileSystem: couldn't get a file system",
              fileSystemType
            ].join( " " ) )
          }
          deferred.reject( anError );
        } );
      } catch ( anError ) {
        deferred.reject( anError );
      }
      return deferred.promise;
    }
    /**
     * Resolves theURI to a fileEntry or directoryEntry, if possible.
     * If `theURL` contains `private` or `localhost` as its first element, it will be removed. If
     * `theURL` does not have a URL scheme, `file://` will be assumed.
     * @method _resolveLocalFileSystemURL
     * @private
     * @param  {String} theURL the path, should start with file://, but if it doesn't we'll add it.
     */
    function _resolveLocalFileSystemURL( theURL ) {
      var deferred = Q.defer();
      if ( DEBUG ) {
        console.log( [ "_resolveLocalFileSystemURL: ", theURL ].join( " " ) )
      }
      try {
        // split the parts of the URL
        var parts = theURL.split( ":" );
        var protocol, path;
        // can only have two parts
        if ( parts.length > 2 ) {
          throw new Error( "The URI is not well-formed; missing protocol: " +
            theURL );
        }
        // if only one part, we assume `file` as the protocol
        if ( parts.length < 2 ) {
          protocol = "file";
          path = parts[ 0 ];
        } else {
          protocol = parts[ 0 ];
          path = parts[ 1 ];
        }
        // split the path components
        var pathComponents = path.split( "/" );
        var newPathComponents = [];
        // iterate over each component and trim as we go
        pathComponents.forEach( function( part ) {
          part = part.trim();
          if ( part !== "" ) { // remove /private if it is the first item in the new array, for iOS sake
            if ( !( ( part === "private" || part === "localhost" ) &&
              newPathComponents.length === 0 ) ) {
              newPathComponents.push( part );
            }
          }
        } );
        // rejoin the path components
        var theNewURI = newPathComponents.join( "/" );
        // add the protocol
        theNewURI = protocol + ":///" + theNewURI;
        // and resolve the URL.
        window.resolveLocalFileSystemURL( theNewURI, function( theEntry ) {
          deferred.resolve( theEntry );
        }, function( anError ) {
          deferred.reject( anError );
        } );
      } catch ( anError ) {
        deferred.reject( anError );
      }
      return deferred.promise;
    }
    /**
     * @typedef {{}} DirectoryEntry
     * HTML5 File API Directory Type
     */
    /**
     * Returns a directory entry based on the path from the parent using
     * the specified options, if specified. `options` takes the form:
     * ` {create: true/false, exclusive true/false }`
     * @method _getDirectoryEntry
     * @private
     * @param  {DirectoryEntry} parent  The parent that path is relative from (or absolute)
     * @param  {String} path    The relative or absolute path or a {DirectoryEntry}
     * @param  {Object} options The options (that is, create the directory if it doesn't exist, etc.)
     * @return {Promise}         The promise
     */
    function _getDirectoryEntry( parent, path, options ) {
      if ( DEBUG ) {
        console.log( [ "_getDirectoryEntry:", parent, path, options ].join( " " ) )
      }
      var deferred = Q.defer();
      try {
        if ( typeof path === "object" ) {
          deferred.resolve( path );
        } else {
          parent.getDirectory( path, options || {}, function success(
            theDirectoryEntry ) {
            deferred.resolve( theDirectoryEntry );
          }, function failure( anError ) {
            deferred.reject( anError );
          } );
        }
      } catch ( anError ) {
        deferred.reject( anError );
      }
      return deferred.promise;
    }
    /**
     * Returns a file entry based on the path from the parent using
     * the specified options. `options` takes the form of `{ create: true/false, exclusive: true/false}`
     * @method getFileEntry
     * @private
     * @param  {DirectoryEntry} parent  The parent that path is relative from (or absolute)
     * @param  {String} path    The relative or absolute path
     * @param  {Object} options The options (that is, create the file if it doesn't exist, etc.)
     * @return {Promise}         The promise
     */
    function _getFileEntry( parent, path, options ) {
      if ( DEBUG ) {
        console.log( [ "_getFileEntry:", parent, path, options ].join( " " ) )
      }
      var deferred = Q.defer();
      try {
        if ( typeof path === "object" ) {
          deferred.resolve( path );
        } else {
          parent.getFile( path, options || {}, function success( theFileEntry ) {
            deferred.resolve( theFileEntry );
          }, function failure( anError ) {
            deferred.reject( anError );
          } );
        }
      } catch ( anError ) {
        deferred.reject( anError );
      }
      return deferred.promise;
    }
    /**
     * @typedef {{}} FileEntry
     * HTML5 File API File Entry
     */
    /**
     * Returns a file object based on the file entry.
     * @method _getFileObject
     * @private
     * @param  {FileEntry} fileEntry The file Entry
     * @return {Promise}           The Promise
     */
    function _getFileObject( fileEntry ) {
      if ( DEBUG ) {
        console.log( [ "_getFileObject:", fileEntry ].join( " " ) )
      }
      var deferred = Q.defer();
      try {
        fileEntry.file( function success( theFile ) {
          deferred.resolve( theFile );
        }, function failure( anError ) {
          deferred.reject( anError );
        } );
      } catch ( anError ) {
        deferred.reject( anError );
      }
      return deferred.promise;
    }
    /**
     * Reads the file contents from a file object. readAsKind indicates how
     * to read the file ("Text", "DataURL", "BinaryString", "ArrayBuffer").
     * @method _readFileContents
     * @private
     * @param  {File} fileObject File to read
     * @param  {String} readAsKind "Text", "DataURL", "BinaryString", "ArrayBuffer"
     * @return {Promise}            The Promise
     */
    function _readFileContents( fileObject, readAsKind ) {
      if ( DEBUG ) {
        console.log( [ "_readFileContents:", fileObject, readAsKind ].join( " " ) )
      }
      var deferred = Q.defer();
      try {
        var fileReader = new FileReader();
        fileReader.onloadend = function( e ) {
          deferred.resolve( e.target.result );
        };
        fileReader.onerror = function( anError ) {
          deferred.reject( anError );
        };
        fileReader[ "readAs" + readAsKind ]( fileObject );
      } catch ( anError ) {
        deferred.reject( anError );
      }
      return deferred.promise;
    }
    /**
     * Creates a file writer for the file entry; `fileEntry` must exist
     * @method _createFileWriter
     * @private
     * @param  {FileEntry} fileEntry The file entry to write to
     * @return {Promise}           the Promise
     */
    function _createFileWriter( fileEntry ) {
      if ( DEBUG ) {
        console.log( [ "_createFileWriter:", fileEntry ].join( " " ) )
      }
      var deferred = Q.defer();
      try {
        var fileWriter = fileEntry.createWriter( function success( theFileWriter ) {
          deferred.resolve( theFileWriter );
        }, function failure( anError ) {
          deferred.reject( anError );
        } );
      } catch ( anError ) {
        deferred.reject( anError );
      }
      return deferred.promise;
    }
    /**
     * @typedef {{}} FileWriter
     * HTML5 File API File Writer Type
     */
    /**
     * Write the contents to the fileWriter; `contents` should be a Blob.
     * @method _writeFileContents
     * @private
     * @param  {FileWriter} fileWriter Obtained from _createFileWriter
     * @param  {*} contents   The contents to write
     * @return {Promise}            the Promise
     */
    function _writeFileContents( fileWriter, contents ) {
      if ( DEBUG ) {
        console.log( [ "_writeFileContents:", fileWriter, contents ].join( " " ) )
      }
      var deferred = Q.defer();
      try {
        fileWriter.onwrite = function( e ) {
          fileWriter.onwrite = function( e ) {
            deferred.resolve( e );
          };
          fileWriter.write( contents );
        };
        fileWriter.onError = function( anError ) {
          deferred.reject( anError );
        };
        fileWriter.truncate( 0 ); // clear out the contents, first
      } catch ( anError ) {
        deferred.reject( anError );
      }
      return deferred.promise;
    }
    /**
     * Copy the file to the specified parent directory, with an optional new name
     * @method _copyFile
     * @private
     * @param  {FileEntry} theFileEntry            The file to copy
     * @param  {DirectoryEntry} theParentDirectoryEntry The parent directory to copy the file to
     * @param  {String} theNewName              The new name of the file ( or undefined simply to copy )
     * @return {Promise}                         The Promise
     */
    function _copyFile( theFileEntry, theParentDirectoryEntry, theNewName ) {
      if ( DEBUG ) {
        console.log( [ "_copyFile:", theFileEntry, theParentDirectoryEntry,
          theNewName
        ].join( " " ) )
      }
      var deferred = Q.defer();
      try {
        theFileEntry.copyTo( theParentDirectoryEntry, theNewName, function success(
          theNewFileEntry ) {
          deferred.resolve( theNewFileEntry );
        }, function failure( anError ) {
          deferred.reject( anError );
        } );
      } catch ( anError ) {
        deferred.reject( anError );
      }
      return deferred.promise;
    }
    /**
     * Move the file to the specified parent directory, with an optional new name
     * @method _moveFile
     * @private
     * @param  {FileEntry} theFileEntry            The file to move or rename
     * @param  {DirectoryEntry} theParentDirectoryEntry The parent directory to move the file to (or the same as the file in order to rename)
     * @param  {String} theNewName              The new name of the file ( or undefined simply to move )
     * @return {Promise}                         The Promise
     */
    function _moveFile( theFileEntry, theParentDirectoryEntry, theNewName ) {
      if ( DEBUG ) {
        console.log( [ "_moveFile:", theFileEntry, theParentDirectoryEntry,
          theNewName
        ].join( " " ) )
      }
      var deferred = Q.defer();
      try {
        theFileEntry.moveTo( theParentDirectoryEntry, theNewName, function success(
          theNewFileEntry ) {
          deferred.resolve( theNewFileEntry );
        }, function failure( anError ) {
          deferred.reject( anError );
        } );
      } catch ( anError ) {
        deferred.reject( anError );
      }
      return deferred.promise;
    }
    /**
     * Remove the file from the file system
     * @method _removeFile
     * @private
     * @param  {FileEntry} theFileEntry The file to remove
     * @return {Promise}              The Promise
     */
    function _removeFile( theFileEntry ) {
      if ( DEBUG ) {
        console.log( [ "_removeFile:", theFileEntry ].join( " " ) )
      }
      var deferred = Q.defer();
      try {
        theFileEntry.remove( function success() {
          deferred.resolve();
        }, function failure( anError ) {
          deferred.reject( anError );
        } );
      } catch ( anError ) {
        deferred.reject( anError );
      }
      return deferred.promise;
    }
    /**
     * Copies a directory to the specified directory, with an optional new name. The directory
     * is copied recursively.
     * @method _copyDirectory
     * @private
     * @param  {DirectoryEntry} theDirectoryEntry       The directory to copy
     * @param  {DirectoryEntry} theParentDirectoryEntry The parent directory to copy the first directory to
     * @param  {String} theNewName              The optional new name for the directory
     * @return {Promise}                         A promise
     */
    function _copyDirectory( theDirectoryEntry, theParentDirectoryEntry, theNewName ) {
      if ( DEBUG ) {
        console.log( [ "_copyDirectory:", theDirectoryEntry,
          theParentDirectoryEntry,
          theNewName
        ].join( " " ) )
      }
      var deferred = Q.defer();
      try {
        theDirectoryEntry.copyTo( theParentDirectoryEntry, theNewName, function success(
          theNewDirectoryEntry ) {
          deferred.resolve( theNewDirectoryEntry );
        }, function failure( anError ) {
          deferred.reject( anError );
        } );
      } catch ( anError ) {
        deferred.reject( anError );
      }
      return deferred.promise;
    }
    /**
     * Moves a directory to the specified directory, with an optional new name. The directory
     * is moved recursively.
     * @method _moveDirectory
     * @private
     * @param  {DirectoryEntry} theDirectoryEntry       The directory to move
     * @param  {DirectoryEntry} theParentDirectoryEntry The parent directory to move the first directory to
     * @param  {String} theNewName              The optional new name for the directory
     * @return {Promise}                         A promise
     */
    function _moveDirectory( theDirectoryEntry, theParentDirectoryEntry, theNewName ) {
      if ( DEBUG ) {
        console.log( [ "_moveDirectory:", theDirectoryEntry,
          theParentDirectoryEntry,
          theNewName
        ].join( " " ) )
      }
      var deferred = Q.defer();
      try {
        theDirectoryEntry.moveTo( theParentDirectoryEntry, theNewName, function success(
          theNewDirectoryEntry ) {
          deferred.resolve( theNewDirectoryEntry );
        }, function failure( anError ) {
          deferred.reject( anError );
        } );
      } catch ( anError ) {
        deferred.reject( anError );
      }
      return deferred.promise;
    }
    /**
     * Removes a directory from the file system. If recursively is true, the directory is removed
     * recursively.
     * @method _removeDirectory
     * @private
     * @param  {DirectoryEntry} theDirectoryEntry The directory to remove
     * @param  {Boolean} recursively       If true, remove recursively
     * @return {Promise}                   The Promise
     */
    function _removeDirectory( theDirectoryEntry, recursively ) {
      if ( DEBUG ) {
        console.log( [ "_removeDirectory:", theDirectoryEntry, "recursively",
          recursively
        ].join( " " ) )
      }
      var deferred = Q.defer();
      try {
        if ( !recursively ) {
          theDirectoryEntry.remove( function success() {
            deferred.resolve();
          }, function failure( anError ) {
            deferred.reject( anError );
          } );
        } else {
          theDirectoryEntry.removeRecursively( function success() {
            deferred.resolve();
          }, function failure( anError ) {
            deferred.reject( anError );
          } );
        }
      } catch ( anError ) {
        deferred.reject( anError );
      }
      return deferred.promise;
    }
    /**
     * Reads the contents of a directory
     * @method _readDirectoryContents
     * @private
     * @param  {DirectoryEntry} theDirectoryEntry The directory to list
     * @return {Promise}                   The promise
     */
    function _readDirectoryContents( theDirectoryEntry ) {
      if ( DEBUG ) {
        console.log( [ "_readDirectoryContents:", theDirectoryEntry ].join( " " ) )
      }

      function readEntries() {
        directoryReader.readEntries( function success( theEntries ) {
          if ( !theEntries.length ) {
            deferred.resolve( entries );
          } else {
            entries = entries.concat( Array.prototype.slice.call( theEntries || [],
              0 ) );
            readEntries();
          }
        }, function failure( anError ) {
          deferred.reject( anError );
        } );
      }
      var deferred = Q.defer();
      try {
        var directoryReader = theDirectoryEntry.createReader();
        var entries = [];
        readEntries();
      } catch ( anError ) {
        deferred.reject( anError );
      }
      return deferred.promise;
    }
    /**
     * @class FileManager
     */
    var _className = "UTIL.FileManager";
    var FileManager = function() {
      var self;
      // determine if we have a `BaseObject` available or not
      var hasBaseObject = ( typeof BaseObject !== "undefined" );
      if ( hasBaseObject ) {
        // if we do, subclass it
        self = new BaseObject();
        self.subclass( _className );
        self.registerNotification( "changedCurrentWorkingDirectory" );
      } else {
        // otherwise, base off {}
        self = {};
      }
      // get the persistent and temporary filesystem constants
      self.PERSISTENT = ( typeof LocalFileSystem !== "undefined" ) ?
        LocalFileSystem.PERSISTENT : window.PERSISTENT;
      self.TEMPORARY = ( typeof LocalFileSystem !== "undefined" ) ?
        LocalFileSystem.TEMPORARY : window.TEMPORARY;
      // determine the various file types we support
      self.FILETYPE = {
        TEXT: "Text",
        DATA_URL: "DataURL",
        BINARY: "BinaryString",
        ARRAY_BUFFER: "ArrayBuffer"
      };
      /**
       * Returns the value of the global `DEBUG` variable.
       * @method getGlobalDebug
       * @returns {Boolean}
       */
      self.getGlobalDebug = function() {
        return DEBUG;
      };
      /**
       * Sets the global DEBUG variable. If `true`, debug messages are logged to the console.
       * @method setGlobalDebug
       * @param {Boolean} debug
       */
      self.setGlobalDebug = function( debug ) {
        DEBUG = debug;
      };
      /**
       * @property globalDebug
       * @type {Boolean} If `true`, logs messages to console as operations occur.
       */
      Object.defineProperty( self, "globalDebug", {
        get: self.getGlobalDebug,
        set: self.setGlobalDebug,
        configurable: true
      } );
      /**
       * the fileSystemType can either be `self.PERSISTENT` or `self.TEMPORARY`, and is only
       * set during an `init` operation. It cannot be set at any other time.
       * @property fileSystemType
       * @type {FileSystem}
       */
      self._fileSystemType = null; // can only be changed during INIT
      self.getFileSystemType = function() {
        return self._fileSystemType;
      };
      Object.defineProperty( self, "fileSystemType", {
        get: self.getFileSystemType,
        configurable: true
      } );
      /**
       * The requested quota -- stored for future reference, since we ask for it
       * specifically during an `init` operation. It cannot be changed.
       * @property requestedQuota
       * @type {Number}
       */
      self._requestedQuota = 0; // can only be changed during INIT
      self.getRequestedQuota = function() {
        return self._requestedQuota;
      };
      Object.defineProperty( self, "requestedQuota", {
        get: self.getRequestedQuota,
        configurable: true
      } );
      /**
       * The actual quota obtained from the system. It cannot be changed, and is
       * only obtained during `init`. The result does not have to match the
       * `requestedQuota`. If it doesn't match, it may be representative of the
       * actual space available, depending on the platform
       * @property actualQuota
       * @type {Number}
       */
      self._actualQuota = 0;
      self.getActualQuota = function() {
        return self._actualQuota;
      };
      Object.defineProperty( self, "actualQuota", {
        get: self.getActualQuota,
        configurable: true
      } );
      /**
       * @typedef {{}} FileSystem
       * HTML5 File API File System
       */
      /**
       * The current filesystem -- either the temporary or persistent one; it can't be changed
       * @property fileSystem
       * @type {FileSystem}
       */
      self._fileSystem = null;
      self.getFileSystem = function() {
        return self._fileSystem;
      };
      Object.defineProperty( self, "fileSystem", {
        get: self.getFileSystem,
        configurable: true
      } );
      /**
       * Current Working Directory Entry
       * @property cwd
       * @type {DirectoryEntry}
       */
      self._root = null;
      self._cwd = null;
      self.getCurrentWorkingDirectory = function() {
        return self._cwd;
      };
      self.setCurrentWorkingDirectory = function( theCWD ) {
        self._cwd = theCWD;
        if ( hasBaseObject ) {
          self.notify( "changedCurrentWorkingDirectory" );
        }
      };
      Object.defineProperty( self, "cwd", {
        get: self.getCurrentWorkingDirectory,
        set: self.setCurrentWorkingDirectory,
        configurable: true
      } );
      Object.defineProperty( self, "currentWorkingDirectory", {
        get: self.getCurrentWorkingDirectory,
        set: self.setCurrentWorkingDirectory,
        configurable: true
      } );
      /**
       * Current Working Directory stack
       * @property _cwds
       * @private
       * @type {Array}
       */
      self._cwds = [];
      /**
       * Push the current working directory on to the stack
       * @method pushCurrentWorkingDirectory
       */
      self.pushCurrentWorkingDirectory = function() {
        self._cwds.push( self._cwd );
      };
      /**
       * Pop the topmost directory on the stack and change to it
       * @method popCurrentWorkingDirectory
       */
      self.popCurrentWorkingDirectory = function() {
        self.setCurrentWorkingDirectory( self._cwds.pop() );
      };
      /**
       * Resolves a URL to a local file system. If the URL scheme is not present, `file`
       * is assumed.
       * @param {String} theURI The URI to resolve
       */
      self.resolveLocalFileSystemURL = function( theURI ) {
        var deferred = Q.defer();
        _resolveLocalFileSystemURL( theURI ).then( function gotEntry( theEntry ) {
          deferred.resolve( theEntry );
        } ).catch( function( anError ) {
          deferred.reject( anError );
        } ).done();
        return deferred.promise;
      };
      /**
       * Returns the file entry for the given path (useful for
       * getting the full path of a file). `options` is of the
       * form `{create: true/false, exclusive: true/false}`
       * @method getFileEntry
       * @param {String} theFilePath The file path or FileEntry object
       * @param {*} options creation options
       */
      self.getFileEntry = function( theFilePath, options ) {
        var deferred = Q.defer();
        _getFileEntry( self._cwd, theFilePath, options ).then( function gotFileEntry(
          theFileEntry ) {
          deferred.resolve( theFileEntry );
        } ).catch( function( anError ) {
          deferred.reject( anError );
        } ).done();
        return deferred.promise;
      };
      /**
       * Returns the file object for a given file (useful for getting
       * the size of a file); `option` is of the form `{create: true/false, exclusive: true/false}`
       * @method getFile
       * @param {String} theFilePath
       * @param {*} option
       */
      self.getFile = function( theFilePath, options ) {
        return self.getFileEntry( theFilePath, options ).then( _getFileObject );
      };
      /**
       * Returns the directory entry for a given path
       * @method getDirectoryEntry
       * @param {String} theDirectoryPath
       * @param {*} options
       */
      self.getDirectoryEntry = function( theDirectoryPath, options ) {
        var deferred = Q.defer();
        _getDirectoryEntry( self._cwd, theDirectoryPath, options ).then( function gotDirectoryEntry(
          theDirectoryEntry ) {
          deferred.resolve( theDirectoryEntry );
        } ).catch( function( anError ) {
          deferred.reject( anError );
        } ).done();
        return deferred.promise;
      };
      /**
       * returns the URL for a given file
       * @method getFileURL
       * @param {String} theFilePath
       * @param {*} options
       */
      self.getFileURL = function( theFilePath, options ) {
        var deferred = Q.defer();
        _getFileEntry( self._cwd, theFilePath, options ).then( function gotFileEntry(
          theFileEntry ) {
          deferred.resolve( theFileEntry.toURL() );
        } ).catch( function( anError ) {
          deferred.reject( anError );
        } ).done();
        return deferred.promise;
      };
      /**
       * Returns a URL for the given directory
       * @method getDirectoryURL
       * @param {String} thePath
       * @param {*} options
       */
      self.getDirectoryURL = function( thePath, options ) {
        var deferred = Q.defer();
        _getDirectoryEntry( self._cwd, thePath || ".", options ).then( function gotDirectoryEntry(
          theDirectoryEntry ) {
          deferred.resolve( theDirectoryEntry.toURL() );
        } ).catch( function( anError ) {
          deferred.reject( anError );
        } ).done();
        return deferred.promise;
      };
      /**
       * Returns the native URL for an entry by combining the `fullPath` of the entry
       * with the `nativeURL` of the `root` directory if absolute or of the `current`
       * directory if not absolute.
       * @method getNativeURL
       * @param {String} theEntry Path of the file or directory; can also be a File/DirectoryEntry
       */
      self.getNativeURL = function( theEntry ) {
        var thePath = theEntry;
        if ( typeof theEntry !== "string" ) {
          thePath = theEntry.fullPath();
        }
        var isAbsolute = ( thePath.substr( 0, 1 ) === "/" );
        var theRootPath = isAbsolute ? self._root.nativeURL : self.cwd.nativeURL;
        return theRootPath + ( isAbsolute ? "" : "/" ) + thePath;
      };
      /**
       * returns the native file path for a given file
       * @method getNativeFileURL
       * @param {String} theFilePath
       * @param {*} options
       */
      self.getNativeFileURL = function( theFilePath, options ) {
        var deferred = Q.defer();
        _getFileEntry( self._cwd, theFilePath, options ).then( function gotFileEntry(
          theFileEntry ) {
          deferred.resolve( theFileEntry.nativeURL );
        } ).catch( function( anError ) {
          deferred.reject( anError );
        } ).done();
        return deferred.promise;
      };
      /**
       * Returns a URL for the given directory
       * @method getNativeDirectoryURL
       * @param {String} thePath
       * @param {*} options
       */
      self.getNativeDirectoryURL = function( thePath, options ) {
        var deferred = Q.defer();
        _getDirectoryEntry( self._cwd, thePath || ".", options ).then( function gotDirectoryEntry(
          theDirectoryEntry ) {
          deferred.resolve( theDirectoryEntry.nativeURL );
        } ).catch( function( anError ) {
          deferred.reject( anError );
        } ).done();
        return deferred.promise;
      };
      /**
       * Change to an arbitrary directory
       * @method changeDirectory
       * @param  {String} theNewPath The path to the directory, relative to cwd
       * @return {Promise}            The Promise
       */
      self.changeDirectory = function( theNewPath ) {
        var deferred = Q.defer();
        _getDirectoryEntry( self._cwd, theNewPath, {} ).then( function gotDirectory(
          theNewDirectory ) {
          self.cwd = theNewDirectory;
        } ).then( function allDone() {
          deferred.resolve( self );
        } ).catch( function( anError ) {
          deferred.reject( anError );
        } ).done();
        return deferred.promise;
      };
      /**
       * Read an arbitrary file's contents.
       * @method readFileContents
       * @param  {String} theFilePath The path to the file, relative to cwd
       * @param  {Object} options     The options to use when opening the file (such as creating it)
       * @param  {String} readAsKind  How to read the file -- best to use self.FILETYPE.TEXT, etc.
       * @return {Promise}             The Promise
       */
      self.readFileContents = function( theFilePath, options, readAsKind ) {
        var deferred = Q.defer();
        _getFileEntry( self._cwd, theFilePath, options || {} ).then( function gotTheFileEntry(
          theFileEntry ) {
          return _getFileObject( theFileEntry );
        } ).then( function gotTheFileObject( theFileObject ) {
          return _readFileContents( theFileObject, readAsKind || "Text" );
        } ).then( function getTheFileContents( theFileContents ) {
          deferred.resolve( theFileContents );
        } ).catch( function( anError ) {
          deferred.reject( anError );
        } ).done();
        return deferred.promise;
      };
      /**
       * Read an arbitrary directory's entries.
       * @method readDirectoryContents
       * @param  {String} theDirectoryPath The path to the directory, relative to cwd; "." if not specified
       * @param  {Object} options          The options to use when opening the directory (such as creating it)
       * @return {Promise}             The Promise
       */
      self.readDirectoryContents = function( theDirectoryPath, options ) {
        var deferred = Q.defer();
        _getDirectoryEntry( self._cwd, theDirectoryPath || ".", options || {} ).then(
          function gotTheDirectoryEntry( theDirectoryEntry ) {
            return _readDirectoryContents( theDirectoryEntry );
          } ).then( function gotTheDirectoryEntries( theEntries ) {
          deferred.resolve( theEntries );
        } ).catch( function( anError ) {
          deferred.reject( anError );
        } ).done();
        return deferred.promise;
      };
      /**
       * Write data to an arbitrary file
       * @method writeFileContents
       * @param  {String} theFilePath The file name to write to, relative to cwd
       * @param  {Object} options     The options to use when opening the file
       * @param  {*} theData     The data to write
       * @return {Promise}             The Promise
       */
      self.writeFileContents = function( theFilePath, options, theData ) {
        var deferred = Q.defer();
        _getFileEntry( self._cwd, theFilePath, options || {
          create: true,
          exclusive: false
        } ).then( function gotTheFileEntry( theFileEntry ) {
          return _createFileWriter( theFileEntry );
        } ).then( function gotTheFileWriter( theFileWriter ) {
          return _writeFileContents( theFileWriter, theData );
        } ).then( function allDone() {
          deferred.resolve( self );
        } ).catch( function( anError ) {
          deferred.reject( anError );
        } ).done();
        return deferred.promise;
      };
      /**
       * Creates an arbitrary directory
       * @method createDirectory
       * @param  {String} theDirectoryPath The path, relative to cwd
       * @return {Promise}                  The Promise
       */
      self.createDirectory = function( theDirectoryPath ) {
        var deferred = Q.defer();
        _getDirectoryEntry( self._cwd, theDirectoryPath, {
          create: true,
          exclusive: false
        } ).then( function gotDirectory( theNewDirectory ) {
          deferred.resolve( theNewDirectory );
        } ).catch( function( anError ) {
          deferred.reject( anError );
        } ).done();
        return deferred.promise;
      };
      /**
       * Copies a file to a new directory, with an optional new name
       * @method copyFile
       * @param  {String} sourceFilePath      Path to file, relative to cwd
       * @param  {String} targetDirectoryPath Path to new directory, relative to cwd
       * @param  {String} withNewName         New name, if desired
       * @return {Promise}                     The Promise
       */
      self.copyFile = function( sourceFilePath, targetDirectoryPath, withNewName ) {
        var deferred = Q.defer();
        var theFileToCopy;
        _getFileEntry( self._cwd, sourceFilePath, {} ).then( function gotFileEntry(
          aFileToCopy ) {
          theFileToCopy = aFileToCopy;
          return _getDirectoryEntry( self._cwd, targetDirectoryPath, {} );
        } ).then( function gotDirectoryEntry( theTargetDirectory ) {
          return _copyFile( theFileToCopy, theTargetDirectory, withNewName );
        } ).then( function allDone( theNewFileEntry ) {
          deferred.resolve( theNewFileEntry );
        } ).catch( function( anError ) {
          deferred.reject( anError );
        } ).done();
        return deferred.promise;
      };
      /**
       * Copies a directory to a new directory, with an optional new name
       * @method copyDirectory
       * @param  {String} sourceDirectoryPath Path to directory, relative to cwd
       * @param  {String} targetDirectoryPath Path to new directory, relative to cwd
       * @param  {String} withNewName         New name, if desired
       * @return {Promise}                     The Promise
       */
      self.copyDirectory = function( sourceDirectoryPath, targetDirectoryPath,
        withNewName ) {
        var deferred = Q.defer();
        var theDirectoryToCopy;
        _getDirectoryEntry( self._cwd, sourceDirectoryPath, {} ).then( function gotSourceDirectoryEntry(
          sourceDirectoryEntry ) {
          theDirectoryToCopy = sourceDirectoryEntry;
          return _getDirectoryEntry( self._cwd, targetDirectoryPath, {} );
        } ).then( function gotTargetDirectoryEntry( theTargetDirectory ) {
          return _copyDirectory( theDirectoryToCopy, theTargetDirectory,
            withNewName );
        } ).then( function allDone( theNewDirectoryEntry ) {
          deferred.resolve( theNewDirectoryEntry );
        } ).catch( function( anError ) {
          deferred.reject( anError );
        } ).done();
        return deferred.promise;
      };
      /**
       * @method moveFile
       * Moves a file to a new directory, with an optional new name
       * @param  {String} sourceFilePath      Path to file, relative to cwd
       * @param  {String} targetDirectoryPath Path to new directory, relative to cwd
       * @param  {String} withNewName         New name, if desired
       * @return {Promise}                     The Promise
       */
      self.moveFile = function( sourceFilePath, targetDirectoryPath, withNewName ) {
        var deferred = Q.defer();
        var theFileToMove;
        _getFileEntry( self._cwd, sourceFilePath, {} ).then( function gotFileEntry(
          aFileToMove ) {
          theFileToMove = aFileToMove;
          return _getDirectoryEntry( self._cwd, targetDirectoryPath, {} );
        } ).then( function gotDirectoryEntry( theTargetDirectory ) {
          return _moveFile( theFileToMove, theTargetDirectory, withNewName );
        } ).then( function allDone( theNewFileEntry ) {
          deferred.resolve( theNewFileEntry );
        } ).catch( function( anError ) {
          deferred.reject( anError );
        } ).done();
        return deferred.promise;
      };
      /**
       * Moves a directory to a new directory, with an optional new name
       * @method moveDirectory
       * @param  {String} sourceDirectoryPath Path to directory, relative to cwd
       * @param  {String} targetDirectoryPath Path to new directory, relative to cwd
       * @param  {String} withNewName         New name, if desired
       * @return {Promise}                     The Promise
       */
      self.moveDirectory = function( sourceDirectoryPath, targetDirectoryPath,
        withNewName ) {
        var deferred = Q.defer();
        var theDirectoryToMove;
        _getDirectoryEntry( self._cwd, sourceDirectoryPath, {} ).then( function gotSourceDirectoryEntry(
          sourceDirectoryEntry ) {
          theDirectoryToMove = sourceDirectoryEntry;
          return _getDirectoryEntry( self._cwd, targetDirectoryPath, {} );
        } ).then( function gotTargetDirectoryEntry( theTargetDirectory ) {
          return _moveDirectory( theDirectoryToMove, theTargetDirectory,
            withNewName );
        } ).then( function allDone( theNewDirectoryEntry ) {
          deferred.resolve( theNewDirectoryEntry );
        } ).catch( function( anError ) {
          deferred.reject( anError );
        } ).done();
        return deferred.promise;
      };
      /**
       * Renames a file to a new name, in the cwd
       * @method renameFile
       * @param  {String} sourceFilePath      Path to file, relative to cwd
       * @param  {String} withNewName         New name
       * @return {Promise}                     The Promise
       */
      self.renameFile = function( sourceFilePath, withNewName ) {
        return self.moveFile( sourceFilePath, ".", withNewName );
      };
      /**
       * Renames a directory to a new name, in the cwd
       * @method renameDirectory
       * @param  {String} sourceDirectoryPath Path to directory, relative to cwd
       * @param  {String} withNewName         New name
       * @return {Promise}                     The Promise
       */
      self.renameDirectory = function( sourceDirectoryPath, withNewName ) {
        return self.moveDirectory( sourceDirectoryPath, ".", withNewName );
      };
      /**
       * Deletes a file
       * @method deleteFile
       * @param  {String} theFilePath Path to file, relative to cwd
       * @return {Promise}             The Promise
       */
      self.deleteFile = function( theFilePath ) {
        var deferred = Q.defer();
        _getFileEntry( self._cwd, theFilePath, {} ).then( function gotTheFileToDelete(
          theFileEntry ) {
          return _removeFile( theFileEntry );
        } ).then( function allDone() {
          deferred.resolve( self );
        } ).catch( function( anError ) {
          deferred.reject( anError );
        } ).done();
        return deferred.promise;
      };
      /**
       * Removes a directory, possibly recursively
       * @method removeDirectory
       * @param  {String} theDirectoryPath path to directory, relative to cwd
       * @param  {Boolean} recursively      If true, recursive remove
       * @return {Promise}                  The promise
       */
      self.removeDirectory = function( theDirectoryPath, recursively ) {
        var deferred = Q.defer();
        _getDirectoryEntry( self._cwd, theDirectoryPath, {} ).then( function gotTheDirectoryToDelete(
          theDirectoryEntry ) {
          return _removeDirectory( theDirectoryEntry, recursively );
        } ).then( function allDone() {
          deferred.resolve( self );
        } ).catch( function( anError ) {
          deferred.reject( anError );
        } ).done();
        return deferred.promise;
      };
      /**
       * Asks the browser for the requested quota, and then requests the file system
       * and sets the cwd to the root directory.
       * @method _initializeFileSystem
       * @private
       * @return {Promise} The promise
       */
      self._initializeFileSystem = function() {
        var deferred = Q.defer();
        _requestQuota( self.fileSystemType, self.requestedQuota ).then( function gotQuota(
          theQuota ) {
          self._actualQuota = theQuota;
          return _requestFileSystem( self.fileSystemType, self.actualQuota );
        } ).then( function gotFS( theFS ) {
          self._fileSystem = theFS;
          //self._cwd = theFS.root;
          return _getDirectoryEntry( theFS.root, "", {} );
        } ).then( function gotRootDirectory( theRootDirectory ) {
          self._root = theRootDirectory;
          self._cwd = theRootDirectory;
        } ).then( function allDone() {
          deferred.resolve( self );
        } ).catch( function( anError ) {
          deferred.reject( anError );
        } ).done();
        return deferred.promise;
      };
      if ( self.overrideSuper ) {
        self.overrideSuper( self.class, "init", self.init );
      }
      /**
       * Initializes the file manager with the requested file system type (self.PERSISTENT or self.TEMPORARY)
       * and requested quota size. Both must be specified.
       * @method init
       * @param {FileSystem} fileSystemType
       * @param {Number} requestedQuota
       */
      self.init = function( fileSystemType, requestedQuota ) {
        if ( self.super ) {
          self.super( _className, "init" );
        }
        if ( typeof fileSystemType === "undefined" ) {
          throw new Error(
            "No file system type specified; specify PERSISTENT or TEMPORARY." );
        }
        if ( typeof requestedQuota === "undefined" ) {
          throw new Error( "No quota requested. If you don't know, specify ZERO." );
        }
        self._requestedQuota = requestedQuota;
        self._fileSystemType = fileSystemType;
        return self._initializeFileSystem(); // this returns a promise, so we can .then after.
      };
      /**
       * Initializes the file manager with the requested file system type (self.PERSISTENT or self.TEMPORARY)
       * and requested quota size. Both must be specified.
       * @method initWithOptions
       * @param {*} options
       */
      self.initWithOptions = function( options ) {
        if ( typeof options === "undefined" ) {
          throw new Error( "No options specified. Need type and quota." );
        }
        if ( typeof options.fileSystemType === "undefined" ) {
          throw new Error(
            "No file system type specified; specify PERSISTENT or TEMPORARY." );
        }
        if ( typeof options.requestedQuota === "undefined" ) {
          throw new Error( "No quota requested. If you don't know, specify ZERO." );
        }
        return self.init( options.fileSystemType, options.requestedQuota );
      };
      return self;
    };
    // meta information
    FileManager.meta = {
      version: '00.04.450',
      class: _className,
      autoInitializable: false,
      categorizable: false
    };
    // assign to `window` if stand-alone
    if ( globalContext ) {
      globalContext.FileManager = FileManager
    }
    // return factory
    return FileManager;
} )( Q, undefined, ( typeof IN_YASMF !== "undefined" ) ? undefined : window );

For more docs, see https://github.com/photokandyStudios/YASMF-Next/wiki/FileManager

Updated to most recent version of FileManager. Example updated as well.

Updated to most recent version of FileManager in order to fix some issues discovered by @chasen. Example jsbin also updated.

What is the status of FileManager now (12/2/16)? Does it still require Q.js? Are there any examples of usage? The referenced jsbin seems to be empty.

Hi Kerry, I'm Rei from Rome, Italy. I have a proprietary file manager that gives me a lot of problems with callbacks, I found your wandering around the web and it seems pretty interesting, I would like to replace it with mine. I wanted to ask you: does your support also the latest versions of Cordova? I'm using 6.3.0 for compatibility gestures with some plugins, but I would like to move on to newer versions, like 8. Thanks, regards. Rei