resumable.js

/*
* MIT Licensed
* http://www.23developer.com/opensource
* http://github.com/23/resumable.js
* Steffen Tiedemann Christensen, steffen@23company.com
*/

(function () {
    "use strict";

    var Resumable = function (opts) {
        if (!(this instanceof Resumable)) {
            return new Resumable(opts);
        }
        this.version = 1.0;
        // SUPPORTED BY BROWSER?
        // Check if these features are support by the browser:
        // - File object type
        // - Blob object type
        // - FileList object type
        // - slicing files
        this.support = (
            (typeof(File) !== 'undefined')
            &&
            (typeof(Blob) !== 'undefined')
            &&
            (typeof(FileList) !== 'undefined')
            &&
            (!!Blob.prototype.webkitSlice || !!Blob.prototype.mozSlice || !!Blob.prototype.slice || false)
        );
        if (!this.support) return (false);


        // PROPERTIES
        var $ = this;
        $.files = [];
        $.defaults = {
            chunkSize: 1 * 1024 * 1024,
            forceChunkSize: false,
            simultaneousUploads: 3,
            fileParameterName: 'file',
            chunkNumberParameterName: 'resumableChunkNumber',
            chunkSizeParameterName: 'resumableChunkSize',
            currentChunkSizeParameterName: 'resumableCurrentChunkSize',
            totalSizeParameterName: 'resumableTotalSize',
            typeParameterName: 'resumableType',
            identifierParameterName: 'resumableIdentifier',
            fileNameParameterName: 'resumableFilename',
            relativePathParameterName: 'resumableRelativePath',
            totalChunksParameterName: 'resumableTotalChunks',
            throttleProgressCallbacks: 0.5,
            query: {},
            headers: {},
            preprocess: null,
            preprocessFile: null,
            method: 'multipart',
            uploadMethod: 'POST',
            testMethod: 'GET',
            prioritizeFirstAndLastChunk: false,
            target: '/',
            testTarget: null,
            parameterNamespace: '',
            testChunks: true,
            generateUniqueIdentifier: null,
            getTarget: null,
            maxChunkRetries: 100,
            chunkRetryInterval: undefined,
            permanentErrors: [400, 404, 409, 415, 500, 501],
            maxFiles: undefined,
            withCredentials: false,
            xhrTimeout: 0,
            clearInput: true,
            chunkFormat: 'blob',
            setChunkTypeFromFile: false,
            maxFilesErrorCallback: function (files, errorCount) {
                var maxFiles = $.getOpt('maxFiles');
                alert('Please upload no more than ' + maxFiles + ' file' + (maxFiles === 1 ? '' : 's') + ' at a time.');
            },
            minFileSize: 1,
            minFileSizeErrorCallback: function (file, errorCount) {
                alert(file.fileName || file.name + ' is too small, please upload files larger than ' + $h.formatSize($.getOpt('minFileSize')) + '.');
            },
            maxFileSize: undefined,
            maxFileSizeErrorCallback: function (file, errorCount) {
                alert(file.fileName || file.name + ' is too large, please upload files less than ' + $h.formatSize($.getOpt('maxFileSize')) + '.');
            },
            fileType: [],
            fileTypeErrorCallback: function (file, errorCount) {
                alert(file.fileName || file.name + ' has type not allowed, please upload files of type ' + $.getOpt('fileType') + '.');
            }
        };
        $.opts = opts || {};
        $.getOpt = function (o) {
            var $opt = this;
            // Get multiple option if passed an array
            if (o instanceof Array) {
                var options = {};
                $h.each(o, function (option) {
                    options[option] = $opt.getOpt(option);
                });
                return options;
            }
            // Otherwise, just return a simple option
            if ($opt instanceof ResumableChunk) {
                if (typeof $opt.opts[o] !== 'undefined') {
                    return $opt.opts[o];
                }
                else {
                    $opt = $opt.fileObj;
                }
            }
            if ($opt instanceof ResumableFile) {
                if (typeof $opt.opts[o] !== 'undefined') {
                    return $opt.opts[o];
                }
                else {
                    $opt = $opt.resumableObj;
                }
            }
            if ($opt instanceof Resumable) {
                if (typeof $opt.opts[o] !== 'undefined') {
                    return $opt.opts[o];
                }
                else {
                    return $opt.defaults[o];
                }
            }
        };

        // EVENTS
        // catchAll(event, ...)
        // fileSuccess(file), fileProgress(file), fileAdded(file, event), filesAdded(files, filesSkipped), fileRetry(file),
        // fileError(file, message), complete(), progress(), error(message, file), pause()
        $.events = [];
        $.on = function (event, callback) {
            $.events.push(event.toLowerCase(), callback);
        };
        $.fire = function () {
            // `arguments` is an object, not array, in FF, so:
            var args = [];
            for (var i = 0; i < arguments.length; i++) args.push(arguments[i]);
            // Find event listeners, and support pseudo-event `catchAll`
            var event = args[0].toLowerCase();
            for (var i = 0; i <= $.events.length; i += 2) {
                if ($.events[i] == event) $.events[i + 1].apply($, args.slice(1));
                if ($.events[i] == 'catchall') $.events[i + 1].apply(null, args);
            }
            if (event == 'fileerror') $.fire('error', args[2], args[1]);
            if (event == 'fileprogress') $.fire('progress');
        };


        // INTERNAL HELPER METHODS (handy, but ultimately not part of uploading)
        var $h = {
            stopEvent: function (e) {
                e.stopPropagation();
                e.preventDefault();
            },
            each: function (o, callback) {
                if (typeof(o.length) !== 'undefined') {
                    for (var i = 0; i < o.length; i++) {
                        // Array or FileList
                        if (callback(o[i]) === false) return;
                    }
                } else {
                    for (i in o) {
                        // Object
                        if (callback(i, o[i]) === false) return;
                    }
                }
            },
            generateUniqueIdentifier: function (file, event) {
                var custom = $.getOpt('generateUniqueIdentifier');
                if (typeof custom === 'function') {
                    return custom(file, event);
                }
                var relativePath = file.webkitRelativePath || file.fileName || file.name; // Some confusion in different versions of Firefox
                var size = file.size;
                return (size + '-' + relativePath.replace(/[^0-9a-zA-Z_-]/img, ''));
            },
            contains: function (array, test) {
                var result = false;

                $h.each(array, function (value) {
                    if (value == test) {
                        result = true;
                        return false;
                    }
                    return true;
                });

                return result;
            },
            formatSize: function (size) {
                if (size < 1024) {
                    return size + ' bytes';
                } else if (size < 1024 * 1024) {
                    return (size / 1024.0).toFixed(0) + ' KB';
                } else if (size < 1024 * 1024 * 1024) {
                    return (size / 1024.0 / 1024.0).toFixed(1) + ' MB';
                } else {
                    return (size / 1024.0 / 1024.0 / 1024.0).toFixed(1) + ' GB';
                }
            },
            getTarget: function (request, params) {
                var target = $.getOpt('target');

                if (request === 'test' && $.getOpt('testTarget')) {
                    target = $.getOpt('testTarget') === '/' ? $.getOpt('target') : $.getOpt('testTarget');
                }

                if (typeof target === 'function') {
                    return target(params);
                }

                var separator = target.indexOf('?') < 0 ? '?' : '&';
                var joinedParams = params.join('&');

                return target + separator + joinedParams;
            }
        };

        var onDrop = function (event) {
            $h.stopEvent(event);

            //handle dropped things as items if we can (this lets us deal with folders nicer in some cases)
            if (event.dataTransfer && event.dataTransfer.items) {
                loadFiles(event.dataTransfer.items, event);
            }
            //else handle them as files
            else if (event.dataTransfer && event.dataTransfer.files) {
                loadFiles(event.dataTransfer.files, event);
            }
        };
        var preventDefault = function (e) {
            e.preventDefault();
        };

        /**
         * processes a single upload item (file or directory)
         * @param {Object} item item to upload, may be file or directory entry
         * @param {string} path current file path
         * @param {File[]} items list of files to append new items to
         * @param {Function} cb callback invoked when item is processed
         */
        function processItem(item, path, items, cb) {
            var entry;
            if (item.isFile) {
                // file provided
                return item.file(function (file) {
                    file.relativePath = path + file.name;
                    items.push(file);
                    cb();
                });
            } else if (item.isDirectory) {
                // item is already a directory entry, just assign
                entry = item;
            } else if (item instanceof File) {
                items.push(item);
            }
            if ('function' === typeof item.webkitGetAsEntry) {
                // get entry from file object
                entry = item.webkitGetAsEntry();
            }
            if (entry && entry.isDirectory) {
                // directory provided, process it
                return processDirectory(entry, path + entry.name + '/', items, cb);
            }
            if ('function' === typeof item.getAsFile) {
                // item represents a File object, convert it
                item = item.getAsFile();
                if (item instanceof File) {
                    item.relativePath = path + item.name;
                    items.push(item);
                }
            }
            cb(); // indicate processing is done
        }


        /**
         * cps-style list iteration.
         * invokes all functions in list and waits for their callback to be
         * triggered.
         * @param  {Function[]}   items list of functions expecting callback parameter
         * @param  {Function} cb    callback to trigger after the last callback has been invoked
         */
        function processCallbacks(items, cb) {
            if (!items || items.length === 0) {
                // empty or no list, invoke callback
                return cb();
            }
            // invoke current function, pass the next part as continuation
            items[0](function () {
                processCallbacks(items.slice(1), cb);
            });
        }

        /**
         * recursively traverse directory and collect files to upload
         * @param  {Object}   directory directory to process
         * @param  {string}   path      current path
         * @param  {File[]}   items     target list of items
         * @param  {Function} cb        callback invoked after traversing directory
         */
        function processDirectory(directory, path, items, cb) {
            var dirReader = directory.createReader();
            var allEntries = [];

            function readEntries() {
                dirReader.readEntries(function (entries) {
                    if (entries.length) {
                        allEntries = allEntries.concat(entries);
                        return readEntries();
                    }

                    // process all conversion callbacks, finally invoke own one
                    processCallbacks(
                        allEntries.map(function (entry) {
                            // bind all properties except for callback
                            return processItem.bind(null, entry, path, items);
                        }),
                        cb
                    );
                });
            }

            readEntries();
        }

        /**
         * process items to extract files to be uploaded
         * @param  {File[]} items items to process
         * @param  {Event} event event that led to upload
         */
        function loadFiles(items, event) {
            if (!items.length) {
                return; // nothing to do
            }
            $.fire('beforeAdd');
            var files = [];
            processCallbacks(
                Array.prototype.map.call(items, function (item) {
                    // bind all properties except for callback
                    return processItem.bind(null, item, "", files);
                }),
                function () {
                    if (files.length) {
                        // at least one file found
                        appendFilesFromFileList(files, event);
                    }
                }
            );
        };

        var appendFilesFromFileList = function (fileList, event) {
            // check for uploading too many files
            var errorCount = 0;
            var o = $.getOpt(['maxFiles', 'minFileSize', 'maxFileSize', 'maxFilesErrorCallback', 'minFileSizeErrorCallback', 'maxFileSizeErrorCallback', 'fileType', 'fileTypeErrorCallback']);
            if (typeof(o.maxFiles) !== 'undefined' && o.maxFiles < (fileList.length + $.files.length)) {
                // if single-file upload, file is already added, and trying to add 1 new file, simply replace the already-added file
                if (o.maxFiles === 1 && $.files.length === 1 && fileList.length === 1) {
                    $.removeFile($.files[0]);
                } else {
                    o.maxFilesErrorCallback(fileList, errorCount++);
                    return false;
                }
            }
            var files = [], filesSkipped = [], remaining = fileList.length;
            var decreaseReamining = function () {
                if (!--remaining) {
                    // all files processed, trigger event
                    if (!files.length && !filesSkipped.length) {
                        // no succeeded files, just skip
                        return;
                    }
                    window.setTimeout(function () {
                        $.fire('filesAdded', files, filesSkipped);
                    }, 0);
                }
            };
            $h.each(fileList, function (file) {
                var fileName = file.name;
                var fileType = file.type; // e.g video/mp4
                if (o.fileType.length > 0) {
                    var fileTypeFound = false;
                    for (var index in o.fileType) {
                        // For good behaviour we do some inital sanitizing. Remove spaces and lowercase all
                        o.fileType[index] = o.fileType[index].replace(/\s/g, '').toLowerCase();

                        // Allowing for both [extension, .extension, mime/type, mime/*]
                        var extension = ((o.fileType[index].match(/^[^.][^/]+$/)) ? '.' : '') + o.fileType[index];

                        if ((fileName.substr(-1 * extension.length).toLowerCase() === extension) ||
                            //If MIME type, check for wildcard or if extension matches the files tiletype
                            (extension.indexOf('/') !== -1 && (
                                (extension.indexOf('*') !== -1 && fileType.substr(0, extension.indexOf('*')) === extension.substr(0, extension.indexOf('*'))) ||
                                fileType === extension
                            ))
                        ) {
                            fileTypeFound = true;
                            break;
                        }
                    }
                    if (!fileTypeFound) {
                        o.fileTypeErrorCallback(file, errorCount++);
                        return false;
                    }
                }

                if (typeof(o.minFileSize) !== 'undefined' && file.size < o.minFileSize) {
                    o.minFileSizeErrorCallback(file, errorCount++);
                    return false;
                }
                if (typeof(o.maxFileSize) !== 'undefined' && file.size > o.maxFileSize) {
                    o.maxFileSizeErrorCallback(file, errorCount++);
                    return false;
                }

                function addFile(uniqueIdentifier) {
                    if (!$.getFromUniqueIdentifier(uniqueIdentifier)) {
                        (function () {
                            file.uniqueIdentifier = uniqueIdentifier;
                            var f = new ResumableFile($, file, uniqueIdentifier);
                            $.files.push(f);
                            files.push(f);
                            f.container = (typeof event != 'undefined' ? event.srcElement : null);
                            window.setTimeout(function () {
                                $.fire('fileAdded', f, event)
                            }, 0);
                        })()
                    } else {
                        filesSkipped.push(file);
                    }
                    ;
                    decreaseReamining();
                }

                // directories have size == 0
                var uniqueIdentifier = $h.generateUniqueIdentifier(file, event);
                if (uniqueIdentifier && typeof uniqueIdentifier.then === 'function') {
                    // Promise or Promise-like object provided as unique identifier
                    uniqueIdentifier
                        .then(
                            function (uniqueIdentifier) {
                                // unique identifier generation succeeded
                                addFile(uniqueIdentifier);
                            },
                            function () {
                                // unique identifier generation failed
                                // skip further processing, only decrease file count
                                decreaseReamining();
                            }
                        );
                } else {
                    // non-Promise provided as unique identifier, process synchronously
                    addFile(uniqueIdentifier);
                }
            });
        };

        // INTERNAL OBJECT TYPES
        function ResumableFile(resumableObj, file, uniqueIdentifier) {
            var $ = this;
            $.opts = {};
            $.getOpt = resumableObj.getOpt;
            $._prevProgress = 0;
            $.resumableObj = resumableObj;
            $.file = file;
            $.fileName = file.fileName || file.name; // Some confusion in different versions of Firefox
            $.size = file.size;
            $.relativePath = file.relativePath || file.webkitRelativePath || $.fileName;
            $.uniqueIdentifier = uniqueIdentifier;
            $._pause = false;
            $.container = '';
            $.preprocessState = 0; // 0 = unprocessed, 1 = processing, 2 = finished
            var _error = uniqueIdentifier !== undefined;

            // Callback when something happens within the chunk
            var chunkEvent = function (event, message) {
                // event can be 'progress', 'success', 'error' or 'retry'
                switch (event) {
                    case 'progress':
                        $.resumableObj.fire('fileProgress', $, message);
                        break;
                    case 'error':
                        $.abort();
                        _error = true;
                        $.chunks = [];
                        $.resumableObj.fire('fileError', $, message);
                        break;
                    case 'success':
                        if (_error) return;
                        $.resumableObj.fire('fileProgress', $); // it's at least progress
                        if ($.isComplete()) {
                            $.resumableObj.fire('fileSuccess', $, message);
                        }
                        break;
                    case 'retry':
                        $.resumableObj.fire('fileRetry', $);
                        break;
                }
            };

            // Main code to set up a file object with chunks,
            // packaged to be able to handle retries if needed.
            $.chunks = [];
            $.abort = function () {
                // Stop current uploads
                var abortCount = 0;
                $h.each($.chunks, function (c) {
                    if (c.status() == 'uploading') {
                        c.abort();
                        abortCount++;
                    }
                });
                if (abortCount > 0) $.resumableObj.fire('fileProgress', $);
            };
            $.cancel = function () {
                // Reset this file to be void
                var _chunks = $.chunks;
                $.chunks = [];
                // Stop current uploads
                $h.each(_chunks, function (c) {
                    if (c.status() == 'uploading') {
                        c.abort();
                        $.resumableObj.uploadNextChunk();
                    }
                });
                $.resumableObj.removeFile($);
                $.resumableObj.fire('fileProgress', $);
            };
            $.retry = function () {
                $.bootstrap();
                var firedRetry = false;
                $.resumableObj.on('chunkingComplete', function () {
                    if (!firedRetry) $.resumableObj.upload();
                    firedRetry = true;
                });
            };
            $.bootstrap = function () {
                $.abort();
                _error = false;
                // Rebuild stack of chunks from file
                $.chunks = [];
                $._prevProgress = 0;
                var round = $.getOpt('forceChunkSize') ? Math.ceil : Math.floor;
                var maxOffset = Math.max(round($.file.size / $.getOpt('chunkSize')), 1);
                for (var offset = 0; offset < maxOffset; offset++) {
                    (function (offset) {
                        window.setTimeout(function () {
                            $.chunks.push(new ResumableChunk($.resumableObj, $, offset, chunkEvent));
                            $.resumableObj.fire('chunkingProgress', $, offset / maxOffset);
                        }, 0);
                    })(offset)
                }
                window.setTimeout(function () {
                    $.resumableObj.fire('chunkingComplete', $);
                }, 0);
            };
            $.progress = function () {
                if (_error) return (1);
                // Sum up progress across everything
                var ret = 0;
                var error = false;
                $h.each($.chunks, function (c) {
                    if (c.status() == 'error') error = true;
                    ret += c.progress(true); // get chunk progress relative to entire file
                });
                ret = (error ? 1 : (ret > 0.99999 ? 1 : ret));
                ret = Math.max($._prevProgress, ret); // We don't want to lose percentages when an upload is paused
                $._prevProgress = ret;
                return (ret);
            };
            $.isUploading = function () {
                var uploading = false;
                $h.each($.chunks, function (chunk) {
                    if (chunk.status() == 'uploading') {
                        uploading = true;
                        return (false);
                    }
                });
                return (uploading);
            };
            $.isComplete = function () {
                var outstanding = false;
                if ($.preprocessState === 1) {
                    return (false);
                }
                $h.each($.chunks, function (chunk) {
                    var status = chunk.status();
                    if (status == 'pending' || status == 'uploading' || chunk.preprocessState === 1) {
                        outstanding = true;
                        return (false);
                    }
                });
                return (!outstanding);
            };
            $.pause = function (pause) {
                if (typeof(pause) === 'undefined') {
                    $._pause = ($._pause ? false : true);
                } else {
                    $._pause = pause;
                }
            };
            $.isPaused = function () {
                return $._pause;
            };
            $.preprocessFinished = function () {
                $.preprocessState = 2;
                $.upload();
            };
            $.upload = function () {
                var found = false;
                if ($.isPaused() === false) {
                    var preprocess = $.getOpt('preprocessFile');
                    if (typeof preprocess === 'function') {
                        switch ($.preprocessState) {
                            case 0:
                                $.preprocessState = 1;
                                preprocess($);
                                return (true);
                            case 1:
                                return (true);
                            case 2:
                                break;
                        }
                    }
                    $h.each($.chunks, function (chunk) {
                        if (chunk.status() == 'pending' && chunk.preprocessState !== 1) {
                            chunk.send();
                            found = true;
                            return (false);
                        }
                    });
                }
                return (found);
            }

            // Bootstrap and return
            $.resumableObj.fire('chunkingStart', $);
            $.bootstrap();
            return (this);
        }


        function ResumableChunk(resumableObj, fileObj, offset, callback) {
            var $ = this;
            $.opts = {};
            $.getOpt = resumableObj.getOpt;
            $.resumableObj = resumableObj;
            $.fileObj = fileObj;
            $.fileObjSize = fileObj.size;
            $.fileObjType = fileObj.file.type;
            $.offset = offset;
            $.callback = callback;
            $.lastProgressCallback = (new Date);
            $.tested = false;
            $.retries = 0;
            $.pendingRetry = false;
            $.preprocessState = 0; // 0 = unprocessed, 1 = processing, 2 = finished

            // Computed properties
            var chunkSize = $.getOpt('chunkSize');
            $.loaded = 0;
            $.startByte = $.offset * chunkSize;
            $.endByte = Math.min($.fileObjSize, ($.offset + 1) * chunkSize);
            if ($.fileObjSize - $.endByte < chunkSize && !$.getOpt('forceChunkSize')) {
                // The last chunk will be bigger than the chunk size, but less than 2*chunkSize
                $.endByte = $.fileObjSize;
            }
            $.xhr = null;

            // test() makes a GET request without any data to see if the chunk has already been uploaded in a previous session
            $.test = function () {
                // Set up request and listen for event
                $.xhr = new XMLHttpRequest();

                var testHandler = function (e) {
                    $.tested = true;
                    var status = $.status();
                    if (status == 'success') {
                        $.callback(status, $.message());
                        $.resumableObj.uploadNextChunk();
                    } else {
                        $.send();
                    }
                };
                $.xhr.addEventListener('load', testHandler, false);
                $.xhr.addEventListener('error', testHandler, false);
                $.xhr.addEventListener('timeout', testHandler, false);

                // Add data from the query options
                var params = [];
                var parameterNamespace = $.getOpt('parameterNamespace');
                var customQuery = $.getOpt('query');
                if (typeof customQuery == 'function') customQuery = customQuery($.fileObj, $);
                $h.each(customQuery, function (k, v) {
                    params.push([encodeURIComponent(parameterNamespace + k), encodeURIComponent(v)].join('='));
                });
                // Add extra data to identify chunk
                params = params.concat(
                    [
                        // define key/value pairs for additional parameters
                        ['chunkNumberParameterName', $.offset + 1],
                        ['chunkSizeParameterName', $.getOpt('chunkSize')],
                        ['currentChunkSizeParameterName', $.endByte - $.startByte],
                        ['totalSizeParameterName', $.fileObjSize],
                        ['typeParameterName', $.fileObjType],
                        ['identifierParameterName', $.fileObj.uniqueIdentifier],
                        ['fileNameParameterName', $.fileObj.fileName],
                        ['relativePathParameterName', $.fileObj.relativePath],
                        ['totalChunksParameterName', $.fileObj.chunks.length]
                    ].filter(function (pair) {
                        // include items that resolve to truthy values
                        // i.e. exclude false, null, undefined and empty strings
                        return $.getOpt(pair[0]);
                    })
                        .map(function (pair) {
                            // map each key/value pair to its final form
                            return [
                                parameterNamespace + $.getOpt(pair[0]),
                                encodeURIComponent(pair[1])
                            ].join('=');
                        })
                );
                // Append the relevant chunk and send it
                $.xhr.open($.getOpt('testMethod'), $h.getTarget('test', params));
                $.xhr.timeout = $.getOpt('xhrTimeout');
                $.xhr.withCredentials = $.getOpt('withCredentials');
                // Add data from header options
                var customHeaders = $.getOpt('headers');
                if (typeof customHeaders === 'function') {
                    customHeaders = customHeaders($.fileObj, $);
                }
                $h.each(customHeaders, function (k, v) {
                    $.xhr.setRequestHeader(k, v);
                });
                $.xhr.send(null);
            };

            $.preprocessFinished = function () {
                $.preprocessState = 2;
                $.send();
            };

            // send() uploads the actual data in a POST call
            $.send = function () {
                var preprocess = $.getOpt('preprocess');
                if (typeof preprocess === 'function') {
                    switch ($.preprocessState) {
                        case 0:
                            $.preprocessState = 1;
                            preprocess($);
                            return;
                        case 1:
                            return;
                        case 2:
                            break;
                    }
                }
                if ($.getOpt('testChunks') && !$.tested) {
                    $.test();
                    return;
                }

                // Set up request and listen for event
                $.xhr = new XMLHttpRequest();

                // Progress
                $.xhr.upload.addEventListener('progress', function (e) {
                    if ((new Date) - $.lastProgressCallback > $.getOpt('throttleProgressCallbacks') * 1000) {
                        $.callback('progress');
                        $.lastProgressCallback = (new Date);
                    }
                    $.loaded = e.loaded || 0;
                }, false);
                $.loaded = 0;
                $.pendingRetry = false;
                $.callback('progress');

                // Done (either done, failed or retry)
                var doneHandler = function (e) {
                    var status = $.status();
                    if (status == 'success' || status == 'error') {
                        $.callback(status, $.message());
                        $.resumableObj.uploadNextChunk();
                    } else {
                        $.callback('retry', $.message());
                        $.abort();
                        $.retries++;
                        var retryInterval = $.getOpt('chunkRetryInterval');
                        if (retryInterval !== undefined) {
                            $.pendingRetry = true;
                            setTimeout($.send, retryInterval);
                        } else {
                            $.send();
                        }
                    }
                };
                $.xhr.addEventListener('load', doneHandler, false);
                $.xhr.addEventListener('error', doneHandler, false);
                $.xhr.addEventListener('timeout', doneHandler, false);

                // Set up the basic query data from Resumable
                var query = [
                    ['chunkNumberParameterName', $.offset + 1],
                    ['chunkSizeParameterName', $.getOpt('chunkSize')],
                    ['currentChunkSizeParameterName', $.endByte - $.startByte],
                    ['totalSizeParameterName', $.fileObjSize],
                    ['typeParameterName', $.fileObjType],
                    ['identifierParameterName', $.fileObj.uniqueIdentifier],
                    ['fileNameParameterName', $.fileObj.fileName],
                    ['relativePathParameterName', $.fileObj.relativePath],
                    ['totalChunksParameterName', $.fileObj.chunks.length],
                ].filter(function (pair) {
                    // include items that resolve to truthy values
                    // i.e. exclude false, null, undefined and empty strings
                    return $.getOpt(pair[0]);
                })
                    .reduce(function (query, pair) {
                        // assign query key/value
                        query[$.getOpt(pair[0])] = pair[1];
                        return query;
                    }, {});
                // Mix in custom data
                var customQuery = $.getOpt('query');
                if (typeof customQuery == 'function') customQuery = customQuery($.fileObj, $);
                $h.each(customQuery, function (k, v) {
                    query[k] = v;
                });

                var func = ($.fileObj.file.slice ? 'slice' : ($.fileObj.file.mozSlice ? 'mozSlice' : ($.fileObj.file.webkitSlice ? 'webkitSlice' : 'slice')));
                var bytes = $.fileObj.file[func]($.startByte, $.endByte, $.getOpt('setChunkTypeFromFile') ? $.fileObj.file.type : "");
                var data = null;
                var params = [];

                var parameterNamespace = $.getOpt('parameterNamespace');
                if ($.getOpt('method') === 'octet') {
                    // Add data from the query options
                    data = bytes;
                    $h.each(query, function (k, v) {
                        params.push([encodeURIComponent(parameterNamespace + k), encodeURIComponent(v)].join('='));
                    });
                } else {
                    // Add data from the query options
                    data = new FormData();
                    $h.each(query, function (k, v) {
                        data.append(parameterNamespace + k, v);
                        params.push([encodeURIComponent(parameterNamespace + k), encodeURIComponent(v)].join('='));
                    });
                    if ($.getOpt('chunkFormat') == 'blob') {
                        data.append(parameterNamespace + $.getOpt('fileParameterName'), bytes, $.fileObj.fileName);
                    }
                    else if ($.getOpt('chunkFormat') == 'base64') {
                        var fr = new FileReader();
                        fr.onload = function (e) {
                            data.append(parameterNamespace + $.getOpt('fileParameterName'), fr.result);
                            $.xhr.send(data);
                        }
                        fr.readAsDataURL(bytes);
                    }
                }

                var target = $h.getTarget('upload', params);
                var method = $.getOpt('uploadMethod');

                $.xhr.open(method, target);
                if ($.getOpt('method') === 'octet') {
                    $.xhr.setRequestHeader('Content-Type', 'application/octet-stream');
                }
                $.xhr.timeout = $.getOpt('xhrTimeout');
                $.xhr.withCredentials = $.getOpt('withCredentials');
                // Add data from header options
                var customHeaders = $.getOpt('headers');
                if (typeof customHeaders === 'function') {
                    customHeaders = customHeaders($.fileObj, $);
                }

                $h.each(customHeaders, function (k, v) {
                    $.xhr.setRequestHeader(k, v);
                });

                if ($.getOpt('chunkFormat') == 'blob') {
                    $.xhr.send(data);
                }
            };
            $.abort = function () {
                // Abort and reset
                if ($.xhr) $.xhr.abort();
                $.xhr = null;
            };
            $.status = function () {
                // Returns: 'pending', 'uploading', 'success', 'error'
                if ($.pendingRetry) {
                    // if pending retry then that's effectively the same as actively uploading,
                    // there might just be a slight delay before the retry starts
                    return ('uploading');
                } else if (!$.xhr) {
                    return ('pending');
                } else if ($.xhr.readyState < 4) {
                    // Status is really 'OPENED', 'HEADERS_RECEIVED' or 'LOADING' - meaning that stuff is happening
                    return ('uploading');
                } else {
                    if ($.xhr.status == 200 || $.xhr.status == 201) {
                        // HTTP 200, 201 (created)
                        return ('success');
                    } else if ($h.contains($.getOpt('permanentErrors'), $.xhr.status) || $.retries >= $.getOpt('maxChunkRetries')) {
                        // HTTP 400, 404, 409, 415, 500, 501 (permanent error)
                        return ('error');
                    } else {
                        // this should never happen, but we'll reset and queue a retry
                        // a likely case for this would be 503 service unavailable
                        $.abort();
                        return ('pending');
                    }
                }
            };
            $.message = function () {
                return ($.xhr ? $.xhr.responseText : '');
            };
            $.progress = function (relative) {
                if (typeof(relative) === 'undefined') relative = false;
                var factor = (relative ? ($.endByte - $.startByte) / $.fileObjSize : 1);
                if ($.pendingRetry) return (0);
                if (!$.xhr || !$.xhr.status) factor *= .95;
                var s = $.status();
                switch (s) {
                    case 'success':
                    case 'error':
                        return (1 * factor);
                    case 'pending':
                        return (0 * factor);
                    default:
                        return ($.loaded / ($.endByte - $.startByte) * factor);
                }
            };
            return (this);
        }

        // QUEUE
        $.uploadNextChunk = function () {
            var found = false;

            // In some cases (such as videos) it's really handy to upload the first
            // and last chunk of a file quickly; this let's the server check the file's
            // metadata and determine if there's even a point in continuing.
            if ($.getOpt('prioritizeFirstAndLastChunk')) {
                $h.each($.files, function (file) {
                    if (file.chunks.length && file.chunks[0].status() == 'pending' && file.chunks[0].preprocessState === 0) {
                        file.chunks[0].send();
                        found = true;
                        return (false);
                    }
                    if (file.chunks.length > 1 && file.chunks[file.chunks.length - 1].status() == 'pending' && file.chunks[file.chunks.length - 1].preprocessState === 0) {
                        file.chunks[file.chunks.length - 1].send();
                        found = true;
                        return (false);
                    }
                });
                if (found) return (true);
            }

            // Now, simply look for the next, best thing to upload
            $h.each($.files, function (file) {
                found = file.upload();
                if (found) return (false);
            });
            if (found) return (true);

            // The are no more outstanding chunks to upload, check is everything is done
            var outstanding = false;
            $h.each($.files, function (file) {
                if (!file.isComplete()) {
                    outstanding = true;
                    return (false);
                }
            });
            if (!outstanding) {
                // All chunks have been uploaded, complete
                $.fire('complete');
            }
            return (false);
        };


        // PUBLIC METHODS FOR RESUMABLE.JS
        $.assignBrowse = function (domNodes, isDirectory) {
            if (typeof(domNodes.length) == 'undefined') domNodes = [domNodes];
            $h.each(domNodes, function (domNode) {
                var input;
                if (domNode.tagName === 'INPUT' && domNode.type === 'file') {
                    input = domNode;
                } else {
                    input = document.createElement('input');
                    input.setAttribute('type', 'file');
                    input.style.display = 'none';
                    domNode.addEventListener('click', function () {
                        input.style.opacity = 0;
                        input.style.display = 'block';
                        input.focus();
                        input.click();
                        input.style.display = 'none';
                    }, false);
                    domNode.appendChild(input);
                }
                var maxFiles = $.getOpt('maxFiles');
                if (typeof(maxFiles) === 'undefined' || maxFiles != 1) {
                    input.setAttribute('multiple', 'multiple');
                } else {
                    input.removeAttribute('multiple');
                }
                if (isDirectory) {
                    input.setAttribute('webkitdirectory', 'webkitdirectory');
                } else {
                    input.removeAttribute('webkitdirectory');
                }
                var fileTypes = $.getOpt('fileType');
                if (typeof (fileTypes) !== 'undefined' && fileTypes.length >= 1) {
                    input.setAttribute('accept', fileTypes.map(function (e) {
                        e = e.replace(/\s/g, '').toLowerCase();
                        if (e.match(/^[^.][^/]+$/)) {
                            e = '.' + e;
                        }
                        return e;
                    }).join(','));
                }
                else {
                    input.removeAttribute('accept');
                }
                // When new files are added, simply append them to the overall list
                input.addEventListener('change', function (e) {
                    appendFilesFromFileList(e.target.files, e);
                    var clearInput = $.getOpt('clearInput');
                    if (clearInput) {
                        e.target.value = '';
                    }
                }, false);
            });
        };
        $.assignDrop = function (domNodes) {
            if (typeof(domNodes.length) == 'undefined') domNodes = [domNodes];

            $h.each(domNodes, function (domNode) {
                domNode.addEventListener('dragover', preventDefault, false);
                domNode.addEventListener('dragenter', preventDefault, false);
                domNode.addEventListener('drop', onDrop, false);
            });
        };
        $.unAssignDrop = function (domNodes) {
            if (typeof(domNodes.length) == 'undefined') domNodes = [domNodes];

            $h.each(domNodes, function (domNode) {
                domNode.removeEventListener('dragover', preventDefault);
                domNode.removeEventListener('dragenter', preventDefault);
                domNode.removeEventListener('drop', onDrop);
            });
        };
        $.isUploading = function () {
            var uploading = false;
            $h.each($.files, function (file) {
                if (file.isUploading()) {
                    uploading = true;
                    return (false);
                }
            });
            return (uploading);
        };
        $.upload = function () {
            // Make sure we don't start too many uploads at once
            if ($.isUploading()) return;
            // Kick off the queue
            $.fire('uploadStart');
            for (var num = 1; num <= $.getOpt('simultaneousUploads'); num++) {
                $.uploadNextChunk();
            }
        };
        $.pause = function () {
            // Resume all chunks currently being uploaded
            $h.each($.files, function (file) {
                file.abort();
            });
            $.fire('pause');
        };
        $.cancel = function () {
            $.fire('beforeCancel');
            for (var i = $.files.length - 1; i >= 0; i--) {
                $.files[i].cancel();
            }
            $.fire('cancel');
        };
        $.progress = function () {
            var totalDone = 0;
            var totalSize = 0;
            // Resume all chunks currently being uploaded
            $h.each($.files, function (file) {
                totalDone += file.progress() * file.size;
                totalSize += file.size;
            });
            return (totalSize > 0 ? totalDone / totalSize : 0);
        };
        $.addFile = function (file, event) {
            appendFilesFromFileList([file], event);
        };
        $.addFiles = function (files, event) {
            appendFilesFromFileList(files, event);
        };
        $.removeFile = function (file) {
            for (var i = $.files.length - 1; i >= 0; i--) {
                if ($.files[i] === file) {
                    $.files.splice(i, 1);
                }
            }
        };
        $.getFromUniqueIdentifier = function (uniqueIdentifier) {
            var ret = false;
            $h.each($.files, function (f) {
                if (f.uniqueIdentifier == uniqueIdentifier) ret = f;
            });
            return (ret);
        };
        $.getSize = function () {
            var totalSize = 0;
            $h.each($.files, function (file) {
                totalSize += file.size;
            });
            return (totalSize);
        };
        $.handleDropEvent = function (e) {
            onDrop(e);
        };
        $.handleChangeEvent = function (e) {
            appendFilesFromFileList(e.target.files, e);
            e.target.value = '';
        };
        $.updateQuery = function (query) {
            $.opts.query = query;
        };

        return (this);
    };


    // Node.js-style export for Node and Component
    if (typeof module != 'undefined') {
        module.exports = Resumable;
    } else if (typeof define === "function" && define.amd) {
        // AMD/requirejs: Define the module
        define(function () {
            return Resumable;
        });
    } else {
        // Browser: Expose to window
        window.Resumable = Resumable;
    }

})();