Add _.mapObject

underscore/underscore-tests.ts

@@ -182,6 +182,10 @@ _.omit({ name: 'moe', age: 50, userid: 'moe1' }, 'name');
 _.omit({ name: 'moe', age: 50, userid: 'moe1' }, 'name', 'age');
 _.omit({ name: 'moe', age: 50, userid: 'moe1' }, ['name', 'age']);
 
+_.mapObject({ a: 1, b: 2 }, val => val * 2) === _.mapObject({ a: 2, b: 4 }, _.identity);
+_.mapObject({ a: 1, b: 2 }, (val, key, o) => o[key] * 2) === _.mapObject({ a: 2, b: 4}, _.identity);
+_.mapObject({ x: "string 1", y: "string 2" }, 'length') === _.mapObject({ x: "string 1", y: "string 2"}, _.property('length'));
+
 var iceCream = { flavor: "chocolate" };
 _.defaults(iceCream, { flavor: "vanilla", sprinkles: "lots" });
 

underscore/underscore.d.ts

@@ -1170,6 +1170,31 @@ interface UnderscoreStatic {
 	* @return List of all the values on `object`.
 	**/
 	values(object: any): any[];
+    
+    /**
+     * Like map, but for objects. Transform the value of each property in turn.
+     * @param object The object to transform
+     * @param iteratee The function that transforms property values
+     * @param context The optional context (value of `this`) to bind to
+     * @return a new _.Dictionary of property values
+     */
+    mapObject<T, U>(object: _.Dictionary<T>, iteratee: (val: T, key: string, object: _.Dictionary<T>) => U, context?: any): _.Dictionary<U>;
+    
+    /**
+     * Like map, but for objects. Transform the value of each property in turn.
+     * @param object The object to transform
+     * @param iteratee The function that tranforms property values
+     * @param context The optional context (value of `this`) to bind to
+     */
+    mapObject<T>(object: any, iteratee: (val: any, key: string, object: any) => T, context?: any): _.Dictionary<T>;
+    
+    /**
+     * Like map, but for objects. Retrieves a property from each entry in the object, as if by _.property
+     * @param object The object to transform
+     * @param iteratee The property name to retrieve
+     * @param context The optional context (value of `this`) to bind to
+     */
+    mapObject(object: any, iteratee: string, context?: any): _.Dictionary<any>;
 
 	/**
 	* Convert an object into a list of [key, value] pairs.