diff --git a/swfobject/swfobject-tests.d.ts b/swfobject/swfobject-tests.d.ts
new file mode 100644
index 0000000000..9bf4d09f7c
--- /dev/null
+++ b/swfobject/swfobject-tests.d.ts
@@ -0,0 +1,3 @@
+/// <reference path="swfobject.d.ts" />
+
+var userAgent = swfobject.ua;
diff --git a/swfobject/swfobject.d.ts b/swfobject/swfobject.d.ts
index 55fe3de4c7..f13f8a87a2 100644
--- a/swfobject/swfobject.d.ts
+++ b/swfobject/swfobject.d.ts
@@ -1,103 +1,105 @@
-// Type definitions for swfobject 2.2
-// https://code.google.com/p/swfobject/
+// Type definitions for swfobject v2.2
+// Project: https://code.google.com/p/swfobject/
+// Definitions by: rou https://github.com/rou
+// Definitions: https://github.com/borisyankov/DefinitelyTyped
 
 declare module swfobject {
-	export var ua: {
-		w3: boolean;
-		pv: number[];
-		wk: any;
-		ie: boolean;
-		win: boolean;
-		mac: boolean;
-	};
+  export var ua: {
+    w3: boolean;
+    pv: number[];
+    wk: any;    // number or boolean
+    ie: boolean;
+    win: boolean;
+    mac: boolean;
+  };
 
-	export function registerObject(
-        objectIdStr: string,
-        swfVersionStr: string,
-        xiSwfUrlStr: string,
-        callbackFn: (callbackObj: ICallbackObj) => void
-        ): void
+  export function registerObject(
+    objectIdStr: string,
+    swfVersionStr: string,
+    xiSwfUrlStr?: string,
+    callbackFn?: (callbackObj: ICallbackObj) => void
+    ): void;
 
-	export function getObjectById(
-		objectIdStr: string
-		): HTMLElement;
+  export function getObjectById(
+    objectIdStr: string
+    ): HTMLElement;
 
-	export function embedSWF(
-		swfUrlStr: string,
-		replaceElemIdStr: string,
-		widthStr: string,
-		heightStr: string,
-		swfVersionStr: string,
-		xiSwfUrlStr: string,
-		flashvarsObj: Object,
-		parObj: Object,
-		attObj: Object,
-		callbackFn: (callbackObj: ICallbackObj) => void
-		): void;
+  export function embedSWF(
+    swfUrlStr: string,
+    replaceElemIdStr: string,
+    widthStr: string,
+    heightStr: string,
+    swfVersionStr: string,
+    xiSwfUrlStr?: string,
+    flashvarsObj?: Object,
+    parObj?: Object,
+    attObj?: Object,
+    callbackFn?: (callbackObj: ICallbackObj) => void
+    ): void;
 
-	export function switchOffAutoHideShow(): void;
+  export function switchOffAutoHideShow(): void;
 
-	export function getFlashPlayerVersion(): IFlashPlayerVersion;
+  export function getFlashPlayerVersion(): IFlashPlayerVersion;
 
-	interface IFlashPlayerVersion {
-		major: number;
-		minor: number;
-		release: number;
-	}
+  interface IFlashPlayerVersion {
+    major: number;
+    minor: number;
+    release: number;
+  }
 
-	export function hasPlayerVersion(
-		rv: string
-		): void;
+  export function hasPlayerVersion(
+    rv: string
+    ): void;
 
-	export function createSWF(
-		attObj: ISwfObjectAttribute,
-		parObj: ISwfObjectParameter,
-		replaceElemIdStr: string
-		): HTMLElement;
+  export function createSWF(
+    attObj: ISwfObjectAttribute,
+    parObj: ISwfObjectParameter,
+    replaceElemIdStr: string
+    ): HTMLElement;
 
-	export function showExpressInstall(
-		att: ISwfObjectAttribute,
-		par: ISwfObjectParameter,
-		replaceElemIdStr: string,
-		callbackFn: (callbackObj: ICallbackObj) => void
-		): void;
+  export function showExpressInstall(
+    att: ISwfObjectAttribute,
+    par: ISwfObjectParameter,
+    replaceElemIdStr: string,
+    callbackFn?: (callbackObj: ICallbackObj) => void
+    ): void;
 
-	export function removeSWF(
-		objElemIdStr: string
-		): void;
+  export function removeSWF(
+    objElemIdStr: string
+    ): void;
 
-	export function createCSS(
-		selStr: string,
-		declStr: string,
-		mediaStr: string,
-		newStyleBoolean: boolean
-		): void;
+  export function createCSS(
+    selStr: string,
+    declStr: string,
+    mediaStr?: string,
+    newStyleBoolean?: boolean
+    ): void;
 
-	export function addDomLoadEvent(
-		fn: () => void
-		): void;
+  export function addDomLoadEvent(
+    fn: () => void
+    ): void;
 
-	export function addLoadEvent(
-		fn: (event?: Event) => void
-		): void;
+  export function addLoadEvent(
+    fn: (event?: Event) => void
+    ): void;
 
-	export function getQueryParamValue(
-		param?: string
-		): string;
+  export function getQueryParamValue(
+    param?: string
+    ): string;
 
-	export interface ISwfObjectAttribute {
-		id?: string;
-		width?: string;
-		height?: string;
-	}
+  export interface ISwfObjectAttribute {
+    id?: string;
+    width?: string;
+    height?: string;
+  }
 
-	export interface ISwfObjectParameter {
-		flashvars?: string;
-	}
+  export interface ISwfObjectParameter {
+    flashvars?: string;
+  }
 
-	export interface ICallbackObj {
-		success: boolean;
-		id: string;
-		ref?: HTMLElement;
-	}
+  export interface ICallbackObj {
+    success: boolean;
+    id: string;
+    ref?: HTMLElement;
+  }
 }