Fixed issue with binding when binding to a falsy object (also added types.isNullOrundefined function).

utils/types.d.ts

@@ -28,12 +28,19 @@
     export function isUndefined(value: any): boolean;
 
     /**
-     * A function that checks if something is defined (not null and not undefined).
+     * A function that checks if something is defined (not undefined).
      * @param value The value which will be checked.
      * Returns true if value is defined.
      */
     export function isDefined(value: any): boolean;
 
+    /**
+     * A function that checks if something is not defined (null or undefined).
+     * @param value The value which will be checked.
+     * Returns true if value is null or undefined.
+     */
+    export function isNullOrUndefined(value: any): boolean;
+
     /**
      * A function that checks if something is a valid function.
      * @param value The value which will be checked.

utils/types.ts

@@ -21,6 +21,10 @@ export function isDefined(value: any): boolean {
     return typeof value !== "undefined";
 }
 
+export function isNullOrUndefined(value: any): boolean {
+    return (typeof value === "undefined") || (value === null);
+}
+
 export function verifyCallback(value: any) {
     if (value && !isFunction(value)) {
         throw new TypeError("Callback must be a valid function.");