diff --git a/gulpfile.js b/gulpfile.js
index 6ac27dc..22c9abd 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -6,38 +6,73 @@ var gulp = require("gulp"),
 	addSrc = require("gulp-add-src"),
 	concat = require("gulp-concat"),
 	jshint = require("gulp-jshint"),
-	KarmaServer = require('karma').Server;
+	KarmaServer = require('karma').Server,
+	path = require("path"),
+	filter = require("gulp-filter");
 
-gulp.task("default", function() {
-	return gulp.src("untar-worker.js")
+gulp.task("build:dev", function() {
+	var f = filter(['*', '!untar-worker.js'], { restore: true });
+
+	return gulp.src(["src/untar.js"])
 		.pipe(sourcemaps.init())
+		.pipe(insert.append("\nworkerScriptUri = 'untar-worker.js';"))
+		.pipe(addSrc(["src/ProgressivePromise.js", "src/untar-worker.js"]))
 		.pipe(jshint())
 		.pipe(jshint.reporter("default"))
 		.pipe(jshint.reporter("fail"))
+		.pipe(insert.prepend('"use strict";\n'))
+		.pipe(f)
+		.pipe(umd({
+			dependencies: function(file) {
+				if (path.basename(file.path) === "untar.js") {
+					return ["ProgressivePromise"];
+				} else {
+					return [];
+				}
+			},
+			exports: function(file) {
+				return path.basename(file.path, path.extname(file.path));
+			},
+			namespace: function(file) {
+				return path.basename(file.path, path.extname(file.path));
+			}
+		}))
+		.pipe(f.restore)
+		.pipe(sourcemaps.write())
+		.pipe(gulp.dest("build/dev"));
+});
+
+gulp.task("build:dist", function() {
+	return gulp.src("src/untar-worker.js")
+		.pipe(jshint())
+		.pipe(jshint.reporter("default"))
+		.pipe(jshint.reporter("fail"))
+		.pipe(insert.prepend('"use strict";\n'))
 		.pipe(uglify())
 		.pipe(insert.transform(function(contents, file) {
-			var str = ["\nvar workerScriptUri = URL.createObjectURL(createBlob([\""];
+			var str = ["\nworkerScriptUri = URL.createObjectURL(createBlob([\""];
 			str.push(contents.replace(/"/g, '\\"'));
 			str.push("\"]));");
 
 			return str.join("");
 		}))
-		.pipe(addSrc("untar.js"))
+		.pipe(addSrc(["src/ProgressivePromise.js", "src/untar.js"]))
 		.pipe(jshint())
 		.pipe(jshint.reporter("default"))
 		.pipe(jshint.reporter("fail"))
 		.pipe(concat("untar.js"))
+		.pipe(insert.prepend('"use strict";\n'))
 		.pipe(umd({
 			exports: function() { return "untar"; },
 			namespace: function() { return "untar"; }
 		}))
-		.pipe(sourcemaps.write())
-		.pipe(gulp.dest("build/dev"))
 		.pipe(uglify())
 		.pipe(gulp.dest("build/dist"));
 });
 
-gulp.task("test", ["default"], function(done) {
+gulp.task("default", ["build:dev", "build:dist"]);
+
+gulp.task("test", ["build:dev"], function(done) {
 	new KarmaServer({
 	    configFile: __dirname + '/karma.conf.js',
 	    singleRun: true
diff --git a/karma.conf.js b/karma.conf.js
index e2e2c52..efd2a53 100644
--- a/karma.conf.js
+++ b/karma.conf.js
@@ -16,9 +16,9 @@ module.exports = function(config) {
     // list of files / patterns to load in the browser
     files: [
       'https://www.promisejs.org/polyfills/promise-6.1.0.js',
-      'test-main.js',
       {pattern: 'build/dev/**/*.js', included: false},
-      {pattern: 'spec/**/*.*', included: false}
+      {pattern: 'spec/**/*.*', included: false},
+      'test-main.js'
     ],
 
 
@@ -53,12 +53,12 @@ module.exports = function(config) {
 
 
     // enable / disable watching file and executing tests whenever any file changes
-    autoWatch: false,
+    autoWatch: true,
 
 
     // start these browsers
     // available browser launchers: https://npmjs.org/browse/keyword/karma-launcher
-    browsers: ['PhantomJS'],
+    browsers: ['Chrome'],
 
     browserNoActivityTimeout: 60000,
 
diff --git a/package.json b/package.json
index b392a05..a8891e3 100644
--- a/package.json
+++ b/package.json
@@ -7,7 +7,7 @@
     "test": "test"
   },
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "test": "gulp test"
   },
   "repository": {
     "type": "git",
@@ -30,6 +30,7 @@
     "gulp": "^3.9.0",
     "gulp-add-src": "^0.2.0",
     "gulp-concat": "^2.6.0",
+    "gulp-filter": "^3.0.1",
     "gulp-insert": "^0.5.0",
     "gulp-jshint": "^1.11.2",
     "gulp-sourcemaps": "^1.5.2",
@@ -37,6 +38,7 @@
     "gulp-umd": "^0.2.0",
     "jasmine-core": "^2.3.4",
     "karma": "^0.13.9",
+    "karma-chrome-launcher": "^0.2.0",
     "karma-jasmine": "^0.3.6",
     "karma-phantomjs-launcher": "^0.2.1",
     "karma-requirejs": "^0.2.2",
diff --git a/spec/ProgressivePromise-spec.js b/spec/ProgressivePromise-spec.js
new file mode 100644
index 0000000..128fcb4
--- /dev/null
+++ b/spec/ProgressivePromise-spec.js
@@ -0,0 +1,51 @@
+define(["ProgressivePromise"], function(ProgressivePromise) {
+
+	describe("ProgressivePromise", function() {
+		it("should report progress events as they happen", function(done) {
+			var p = new ProgressivePromise(function(resolve, reject, progress) {
+				setTimeout(function() { progress(1); }, 5);
+				setTimeout(function() { progress(2); }, 10);
+				setTimeout(resolve, 15);
+			});
+
+			var r = [];
+
+			p.progress(function(value) {
+				r.push(value);
+			});
+
+			p.then(function() {
+				if (r[0] === 1 && r[1] === 2) {
+					done();
+				} else {
+					done.fail();
+				}
+			});
+		});
+
+		it("should report progress events after they've happened", function(done) {
+			var p = new ProgressivePromise(function(resolve, reject, progress) {
+				progress(1);
+				progress(2);
+				resolve();
+			});
+
+			setTimeout(function() {
+				var r = [];
+
+				p.progress(function(value) {
+					r.push(value);
+				});
+
+				p.then(function() {
+					if (r[0] === 1 && r[1] === 2) {
+						done();
+					} else {
+						done.fail();
+					}
+				});
+			}, 5);
+		});
+	});
+
+});
diff --git a/spec/untar-spec.js b/spec/untar-spec.js
index ed9803d..631300a 100644
--- a/spec/untar-spec.js
+++ b/spec/untar-spec.js
@@ -1,18 +1,37 @@
-define(["build/dev/untar"], function(untar) {
+define(["untar"], function(untar) {
+
 	describe("untar", function() {
-		it("should unpack 3 files and a directory with 3 files", function(done) {
-			untar("/base/spec/data/test.tar", {
-				onExtract: function(file) { done(); }
-			}).then(
+
+		console.log("untar: " + JSON.stringify(untar));
+
+		var fileNames = [
+			"1.txt",
+			"2.txt",
+			"3.txt",
+			"directory/",
+			"directory/1.txt",
+			"directory/2.txt",
+			"directory/3.txt"
+		];
+
+		it("should unpack 3 specific files and a directory with 3 specific files", function(done) {
+			var i = 0;
+
+			untar("/base/spec/data/test.tar").then(
 				function(files) {
-					expect(files.length).toBe(6);
+					expect(files.length).toBe(7);
 					done();
 				},
 				function(err) {
 					done.fail(JSON.stringify(err));
+				},
+				function(file) {
+					expect(file).toBeDefined();
+					expect(file.name).toBe(fileNames[i]);
+					i += 1;
 				}
 			);
 		}, 20000);
 	});	
-});
 
+});
diff --git a/src/ProgressivePromise.js b/src/ProgressivePromise.js
new file mode 100644
index 0000000..846fd22
--- /dev/null
+++ b/src/ProgressivePromise.js
@@ -0,0 +1,51 @@
+/* globals window: false, Promise: false */
+
+/**
+Returns a Promise decorated with a progress() event.
+*/
+function ProgressivePromise(fn) {
+	if (typeof Promise !== "function") {
+		throw new Error("Promise implementation not available in this environment.");
+	}
+
+	var progressCallbacks = [];
+	var progressHistory = [];
+
+	function doProgress(value) {
+		for (var i = 0, l = progressCallbacks.length; i < l; ++i) {
+			progressCallbacks[i](value);
+		}
+
+		progressHistory.push(value);
+	}
+
+	var promise = new Promise(function(resolve, reject) {
+		fn(resolve, reject, doProgress);
+	});
+
+	promise.progress = function(cb) {
+		if (typeof cb !== "function") {
+			throw new Error("cb is not a function.");
+		}
+
+		// Report the previous progress history
+		for (var i = 0, l = progressHistory.length; i < l; ++i) {
+			cb(progressHistory[i]);
+		}
+
+		progressCallbacks.push(cb);
+		return promise;
+	};
+
+	promise.then = function(onSuccess, onFail, onProgress) {
+		Promise.prototype.then.call(promise, onSuccess, onFail);
+
+		if (onProgress !== undefined) {
+			promise.progress(onProgress);
+		}
+		
+		return promise;
+	};
+
+	return promise;
+}
\ No newline at end of file
diff --git a/src/createBlob.js b/src/createBlob.js
new file mode 100644
index 0000000..a93f79f
--- /dev/null
+++ b/src/createBlob.js
@@ -0,0 +1,20 @@
+"use strict";
+
+var createBlob = (function() {
+	if (typeof window.Blob === "function") {
+		return function(dataArray) { return new Blob(dataArray); };
+	} else {
+		var BBuilder = window.BlobBuilder || window.WebKitBlobBuilder;
+
+		return function(dataArray) {
+			var builder = new BBuilder();
+
+			for (var i = 0; i < dataArray.length; ++i) {
+				var v = dataArray[i];
+				builder.append(v);
+			}
+
+			return builder.getBlob();
+		};
+	}
+}());
\ No newline at end of file
diff --git a/src/untar-worker.js b/src/untar-worker.js
new file mode 100644
index 0000000..db2db5f
--- /dev/null
+++ b/src/untar-worker.js
@@ -0,0 +1,181 @@
+/* globals postMessage: false, DataView: false, self: false, window: false, ArrayBuffer: false, Uint8Array: false */
+
+function UntarWorker() {
+
+}
+
+UntarWorker.prototype = {
+	onmessage: function(msg) {
+		try {
+			if (msg.data.type === "extract") {
+				this.untarBuffer(msg.data.buffer);
+			} else {
+				throw new Error("Unknown message type: " + msg.data.type);
+			}
+		} catch (err) {
+			this.postError(err);
+		}
+	},
+
+ 	postError: function(err) {
+		this.postMessage({ type: "error", data: err });
+	},
+
+	postLog: function(level, msg) {
+		this.postMessage({ type: "log", data: { level: level, msg: msg }});
+	},
+
+	untarBuffer: function(arrayBuffer) {
+		try {
+			var tarFileStream = new UntarFileStream(arrayBuffer);
+			while (tarFileStream.hasNext()) {
+				var file = tarFileStream.next();
+
+				this.postMessage({ type: "extract", data: file }, [file.buffer]);
+			}
+
+			this.postMessage({ type: "complete" });
+		} catch (err) {
+			this.postError(err);
+		}
+	},
+
+	postMessage: function(msg, transfers) {
+		self.postMessage(msg, transfers);
+	}
+};
+
+if (typeof self !== "undefined") {
+	// We're running in a worker thread
+	var worker = new UntarWorker();
+	self.onmessage = function(msg) { worker.onmessage(msg); };
+}
+
+function TarFile() {
+
+}
+
+function UntarStream(arrayBuffer) {
+	this._bufferView = new DataView(arrayBuffer);
+	this._position = 0;
+}
+
+UntarStream.prototype = {
+	readString: function(charCount) {
+		//console.log("readString: position " + this.position() + ", " + charCount + " chars");
+		var charSize = 1;
+		var byteCount = charCount * charSize;
+
+		var charCodes = [];
+
+		for (var i = 0; i < charCount; ++i) {
+			var charCode = this._bufferView.getUint8(this.position() + (i * charSize), true);
+			if (charCode !== 0) {
+				charCodes.push(charCode);
+			} else {
+				break;
+			}
+		}
+
+		this.seek(byteCount);
+
+		return String.fromCharCode.apply(null, charCodes);
+	},
+
+	readBuffer: function(byteCount) {
+		var buf;
+
+		if (typeof ArrayBuffer.prototype.slice === "function") {
+			buf = this._bufferView.buffer.slice(this.position(), this.position() + byteCount);
+		} else {
+			buf = new ArrayBuffer(byteCount);
+			var target = new Uint8Array(buf);
+			var src = new Uint8Array(this._bufferView.buffer, this.position(), byteCount);
+			target.set(src);
+		}
+
+		this.seek(byteCount);
+		return buf;
+	},
+
+	seek: function(byteCount) {
+		this._position += byteCount;
+	},
+
+	peekUint32: function() {
+		return this._bufferView.getUint32(this.position(), true);
+	},
+
+	position: function(newpos) {
+		if (newpos === undefined) {
+			return this._position;
+		} else {
+			this._position = newpos;
+		}
+	},
+
+	size: function() {
+		return this._bufferView.byteLength;
+	}
+};
+
+function UntarFileStream(arrayBuffer) {
+	this._stream = new UntarStream(arrayBuffer);
+}
+
+UntarFileStream.prototype = {
+	hasNext: function() {
+		// A tar file ends with 4 zero bytes
+		return this._stream.position() + 4 < this._stream.size() && this._stream.peekUint32() !== 0;
+	},
+
+	next: function() {
+		var stream = this._stream;
+		var file = new TarFile();
+
+		var headerBeginPos = stream.position();
+		var dataBeginPos = headerBeginPos + 512;
+
+		// Read header
+		file.name = stream.readString(100);
+		file.mode = stream.readString(8);
+		file.uid = stream.readString(8);
+		file.gid = stream.readString(8);
+		file.size = parseInt(stream.readString(12), 8);
+		file.modificationTime = parseInt(stream.readString(12), 8);
+		file.checksum = stream.readString(8);
+		file.type = stream.readString(1);
+		file.linkname = stream.readString(1);
+		file.ustarFormat = stream.readString(6);
+
+		if (file.ustarFormat === "ustar") {
+			file.version = stream.readString(2);
+			file.uname = stream.readString(32);
+			file.gname = stream.readString(32);
+			file.devmajor = stream.readString(8);
+			file.devminor = stream.readString(8);
+			file.namePrefix = stream.readString(155);
+
+			if (file.namePrefix.length > 0) {
+				file.name = file.namePrefix + file.name;
+			}
+		}
+
+		stream.position(dataBeginPos);
+
+		// Normal file is either "\0" or 0.
+		if (file.type === "0" || file.type === "\0") {
+			file.buffer = stream.readBuffer(file.size);
+		} else if (file.type == 5) {
+			// Directory - should we do anything with this? Nope!
+		} else {
+			// We only care about real files, not symlinks.
+		}
+
+		// File data is padded to reach a 512 byte boundary; skip the padded bytes.
+		var dataEndPos = dataBeginPos + (file.size > 0 ? file.size + (512 - file.size % 512) : 0);
+		stream.position(dataEndPos);
+
+		return file;
+	}
+};
\ No newline at end of file
diff --git a/src/untar.js b/src/untar.js
new file mode 100644
index 0000000..4bbd4b3
--- /dev/null
+++ b/src/untar.js
@@ -0,0 +1,82 @@
+/* globals window: false, Blob: false, Promise: false, console: false, Worker: false, ProgressivePromise: false */
+
+var workerScriptUri; // Included at compile time
+
+var URL = window.URL || window.webkitURL;
+
+var createBlob = (function() {
+	if (typeof window.Blob === "function") {
+		return function(dataArray) { return new Blob(dataArray); };
+	} else {
+		var BBuilder = window.BlobBuilder || window.WebKitBlobBuilder;
+
+		return function(dataArray) {
+			var builder = new BBuilder();
+
+			for (var i = 0; i < dataArray.length; ++i) {
+				var v = dataArray[i];
+				builder.append(v);
+			}
+
+			return builder.getBlob();
+		};
+	}
+}());
+
+/**
+Returns a ProgressivePromise.
+*/
+function untar(arrayBuffer) {
+	if (!window.Worker) {
+		throw new Error("Worker implementation not available in this environment.");
+	}
+
+	return new ProgressivePromise(function(resolve, reject, progress) {
+		var worker = new Worker(workerScriptUri);
+
+		var files = [];
+
+		worker.onmessage = function(message) {
+			message = message.data;
+
+			switch (message.type) {
+				case "log":
+					console[message.data.level]("Worker: " + message.data.msg);
+					break;
+				case "extract":
+					var file = decorateExtractedFile(message.data);
+					files.push(file);
+					progress(file);
+					break;
+				case "complete":
+					resolve(files);
+					break;
+				case "error":
+					reject(message.data);
+					break;
+				default:
+					reject(new Error("Unknown message from worker: " + message.type));
+					break;
+			}
+		};
+
+		//console.info("Sending arraybuffer to worker for extraction.");
+		worker.postMessage({ type: "extract", buffer: arrayBuffer }, [arrayBuffer]);
+	});
+}
+
+function decorateExtractedFile(file) {
+	file.blob = createBlob([file.buffer]);
+	delete file.buffer;
+
+	var blobUrl;
+	file.getObjectUrl = function() {
+		if (!blobUrl) {
+			blobUrl = URL.createObjectURL(file.blob);
+		}
+
+		return blobUrl;
+	};
+
+	return file;
+}
\ No newline at end of file
diff --git a/test-main.js b/test-main.js
index c2173ad..08a1383 100644
--- a/test-main.js
+++ b/test-main.js
@@ -8,13 +8,13 @@ Object.keys(window.__karma__.files).forEach(function(file) {
     // If you require sub-dependencies of test files to be loaded as-is (requiring file extension)
     // then do not normalize the paths
     var normalizedTestModule = file.replace(/^\/base\/|\.js$/g, '');
-    allTestFiles.push(normalizedTestModule);
+    allTestFiles.push("../../" + normalizedTestModule);
   }
 });
 
 require.config({
   // Karma serves files under /base, which is the basePath from your config file
-  baseUrl: '/base',
+  baseUrl: '/base/build/dev',
 
   // dynamically load all test files
   deps: allTestFiles,
diff --git a/untar-worker.js b/untar-worker.js
deleted file mode 100644
index 833e196..0000000
--- a/untar-worker.js
+++ /dev/null
@@ -1,165 +0,0 @@
-/* globals postMessage: false, DataView: false, self: false, onmessage: true */
-/* jshint -W097 */
-"use strict";
-
-onmessage = function(e) {
-	postMessage("test");
-};
-
-self.onmessage = function(msg) {
-	postLog("info", "Received message.");
-	try {
-		if (msg.data.type === "extract") {
-			untarBuffer(msg.data.buffer);
-		} else {
-			throw new Error("Unknown message type.");
-		}
-	} catch (err) {
-		postError(err);
-	}
-};
-
-function postError(err) {
-	postMessage({ type: "error", data: err });
-}
-
-function postLog(level, msg) {
-	postMessage({ type: "log", data: { level: level, msg: msg }});
-}
-
-function untarBuffer(arrayBuffer) {
-	try {
-		postLog("info", "buffer size: " + arrayBuffer.byteLength);
-		var tarFileStream = new TarFileStream(arrayBuffer);
-		while (tarFileStream.hasNext()) {
-			var file = tarFileStream.next();
-
-			if (file.buffer) {
-				postMessage({ type: "extract", data: file }, [file.buffer]);
-			}
-		}
-
-		postMessage({ type: "complete" });
-	} catch (err) {
-		postError(err);
-	}
-}
-
-function TarFile() {
-
-}
-
-TarFile.prototype = {
-
-};
-
-function Stream(arrayBuffer) {
-	this._bufferView = new DataView(arrayBuffer);
-	this._position = 0;
-}
-
-Stream.prototype = {
-	readString: function(charCount) {
-		var charSize = 1;
-		var byteCount = charCount * charSize;
-
-		var charCodes = [];
-
-		for (var i = 0; i < charCount; ++i) {
-			var charCode = this._bufferView.getUint8(this.position() + (i * charSize));
-			if (charCode !== 0) {
-				charCodes.push(charCode);
-			} else {
-				break;
-			}
-		}
-
-		this.seek(byteCount);
-
-		return String.fromCharCode.apply(null, charCodes);
-	},
-
-	readBuffer: function(byteCount) {
-		return this._bufferView.buffer.slice(this._position, byteCount);
-	},
-
-	seek: function(byteCount) {
-		this._position += byteCount;
-	},
-
-	peekUint32: function() {
-		return this._bufferView.getUint32(this.position());
-	},
-
-	position: function(newpos) {
-		if (newpos === undefined) {
-			return this._position;
-		} else {
-			this._position = newpos;
-		}
-	},
-
-	size: function() {
-		return this._bufferView.byteLength;
-	}
-};
-
-function TarFileStream(arrayBuffer) {
-	this._stream = new Stream(arrayBuffer);
-}
-
-TarFileStream.prototype = {
-	hasNext: function() {
-		return this._stream.position() < this._stream.size() && this._stream.peekUint32() !== 0;
-	},
-
-	next: function() {
-		var stream = this._stream;
-		var file = new TarFile();
-
-		var headerBeginPos = stream.position;
-		var dataBeginPos = headerBeginPos + 512;
-
-		// Read header
-		file.name = stream.readString(100);
-		file.mode = stream.readString(8);
-		file.uid = stream.readString(8);
-		file.gid = stream.readString(8);
-		file.size = parseInt(stream.readString(12), 8);
-		file.modificationTime = parseInt(stream.readString(12), 8);
-		file.checksum = stream.readString(8);
-		file.type = stream.readString(1);
-		file.linkname = stream.readString(1);
-		file.ustarFormat = stream.readString(6);
-
-		if (file.ustarFormat === "ustar") {
-			file.version = stream.readString(2);
-			file.uname = stream.readString(32);
-			file.gname = stream.readString(32);
-			file.devmajor = stream.readString(8);
-			file.devminor = stream.readString(8);
-			file.namePrefix = stream.readString(155);
-
-			if (file.namePrefix.length > 0) {
-				file.name = file.namePrefix + file.name;
-			}
-		}
-
-		stream.position(dataBeginPos);
-
-		// Normal file is either "\0" or 0.
-		if (file.type === 0 || file.type === "\0") {
-			file.buffer = stream.readBuffer(file.size);
-		} else if (file.type == 5) {
-			// Directory - should we do anything with this? Nope!
-		} else {
-			// We only care about real files, not symlinks.
-		}
-
-		// File data is padded to reach a 512 byte boundary; skip the padded bytes.
-		var bytesToSkipCount = 512 - file.size % 512;
-		stream.seek(bytesToSkipCount);
-
-		return file;
-	}
-};
\ No newline at end of file
diff --git a/untar.js b/untar.js
deleted file mode 100644
index fa5809e..0000000
--- a/untar.js
+++ /dev/null
@@ -1,178 +0,0 @@
-/* globals window: false, Blob: false, Promise: false, console: false, XMLHttpRequest: false, Worker: false */
-/* jshint -W097 */
-"use strict";
-
-var workerScriptUri; // Included at compile time
-
-var URL = window.URL || window.webkitURL;
-
-var createBlob = (function() {
-	if (typeof window.Blob === "function") {
-		return function(dataArray) { return new Blob(dataArray); };
-	} else {
-		var BlobBuilder = window.BlobBuilder || window.WebKitBlobBuilder;
-
-		return function(dataArray) {
-			var builder = new BlobBuilder();
-
-			for (var i = 0; i < dataArray.length; ++i) {
-				builder.append(dataArray[i]);
-			}
-
-			return builder.getBlob();
-		};
-	}
-}());
-
-function createBlob(dataArray) {
-	if (typeof window.Blob === "function") {
-		return new Blob(dataArray);
-	} else {
-		var BlobBuilder = window.BlobBuilder || window.WebKitBlobBuilder;
-		var builder = new BlobBuilder();
-
-		for (var i = 0; i < dataArray.length; ++i) {
-			builder.append(dataArray[i]);
-		}
-
-		return builder.getBlob();
-	}
-}
-
-function loadArrayBuffer(uri) {
-	console.info("loadArrayBuffer called");
-
-	return new Promise(function(resolve, reject) {
-		var request = new XMLHttpRequest();
-
-		/*
-		request.addEventListener("progress", function(e) {
-			postMessage({ type: "loading", data: e });
-		});
-		*/
-
-		request.addEventListener("load", function(e) {
-			if (request.status >= 200 && request.status < 400) {
-				resolve(request.response);
-			} else {
-				reject(new Error(request.status + " " + request.statusText));
-			}
-		});
-
-		request.addEventListener("error", function(err) { reject(err); });
-		request.addEventListener("abort", function(err) { reject(err); });
-
-		request.open("GET", uri, true);
-		request.responseType = "arraybuffer";
-		request.send();
-	});
-}
-
-/**
-source	= ArrayBuffer or a url string. If an ArrayBuffer, it will be transfered to the web worker and will thus not be available in the window after.
-options	= {
-	onComplete,
-	onLoading, // When downloading the tar from a url.
-	onExtract,
-	onError
-}
-*/
-function untar(source, options) {
-	console.info("untar called");
-
-	if (typeof Promise !== "function") {
-		throw new Error("Promise implementation not available in this environment.");
-	}
-
-	if (!window.Worker) {
-		throw new Error("Worker implementation not available in this environment.");
-	}
-
-	options = options || {};
-
-	return new Promise(function(resolve, reject) {
-		var noop = function() { };
-		var onComplete = options.onComplete || noop;
-		var onLoading = options.onProgress || noop;
-		var onExtract = options.onExtract || noop;
-		var onError = options.onError || noop;
-
-		var worker = new Worker(workerScriptUri);
-
-		var files = [];
-		var msgData;
-
-		worker.onmessage = function(message) {
-			message = message.data;
-
-			switch (message.type) {
-				case "log":
-					console[message.data.level]("Worker: " + message.data.msg);
-					break;
-				case "loading":
-					onLoading(message.data);
-					break;
-				case "extract":
-					msgData = new TarFile(message.data);
-					files.push(msgData);
-					onExtract(msgData);
-					break;
-				case "complete":
-					onComplete(files);
-					resolve(files);
-					break;
-				case "error":
-					msgData = message.data;
-					onError(msgData);
-					reject(msgData);
-					break;
-				default:
-					msgData = new Error("Unknown message from worker: " + message.type);
-					onError(msgData);
-					reject(msgData);
-					break;
-			}
-		};
-
-		if (typeof source === "string") {
-			loadArrayBuffer(source).then(
-				function(buffer) {
-					console.info("Loaded tar file, sending to worker for extraction.");
-					worker.postMessage({ type: "extract", buffer: buffer }, [buffer]);
-				},
-				function(err) {
-					onError(err);
-					reject(err);
-				}
-			);
-		} else {
-			console.info("Sending tar file to worker for extraction.");
-			worker.postMessage({ type: "extract", buffer: source }, [source]);
-		}
-	});
-}
-
-function TarFile(orig) {
-	this._blobUrl = null;
-
-	for (var p in orig) {
-		switch (p) {
-			case "buffer":
-				this.blob = createBlob([orig.buffer]);
-				break;
-			default:
-				this[p] = orig[p];
-				break;
-		}
-	}
-}
-
-TarFile.prototype = {
-	getObjectUrl: function() {
-		if (!this._blobUrl) {
-			this._blobUrl = URL.createObjectURL(this.blob);
-		}
-
-		return this._blobUrl;
-	}
-};