lodash: improved signatures of the method _.findKey

lodash/lodash-tests.ts

@@ -2013,28 +2013,43 @@ result = <DefaultsDeepResult>_(TestDefaultsDeepObject).defaultsDeep<DefaultsDeep
 
 // _.findKey
 module TestFindKey {
-    let predicateFn: (value: any, key?: string, object?: {}) => boolean;
     let result: string;
 
-    result = _.findKey<{a: string;}>({a: ''});
+    {
+        let predicateFn: (value: any, key?: string, object?: {}) => boolean;
 
-    result = _.findKey<{a: string;}>({a: ''}, predicateFn);
-    result = _.findKey<{a: string;}>({a: ''}, predicateFn, any);
+        result = _.findKey<{a: string;}>({a: ''});
 
-    result = _.findKey<{a: string;}>({a: ''}, '');
-    result = _.findKey<{a: string;}>({a: ''}, '', any);
+        result = _.findKey<{a: string;}>({a: ''}, predicateFn);
+        result = _.findKey<{a: string;}>({a: ''}, predicateFn, any);
 
-    result = _.findKey<{a: number;}, {a: string;}>({a: ''}, {a: 42});
 
-    result = _<{a: string;}>({a: ''}).findKey();
+        result = _.findKey<{a: string;}>({a: ''}, '');
+        result = _.findKey<{a: string;}>({a: ''}, '', any);
 
-    result = _<{a: string;}>({a: ''}).findKey(predicateFn);
-    result = _<{a: string;}>({a: ''}).findKey(predicateFn, any);
+        result = _.findKey<{a: number;}, {a: string;}>({a: ''}, {a: 42});
 
-    result = _<{a: string;}>({a: ''}).findKey('');
-    result = _<{a: string;}>({a: ''}).findKey('', any);
+        result = _<{a: string;}>({a: ''}).findKey();
 
-    result = _<{a: string;}>({a: ''}).findKey<{a: number;}>({a: 42});
+        result = _<{a: string;}>({a: ''}).findKey(predicateFn);
+        result = _<{a: string;}>({a: ''}).findKey(predicateFn, any);
+
+
+        result = _<{a: string;}>({a: ''}).findKey('');
+        result = _<{a: string;}>({a: ''}).findKey('', any);
+
+        result = _<{a: string;}>({a: ''}).findKey<{a: number;}>({a: 42});
+    }
+
+    {
+        let predicateFn: (value: string, key?: string, collection?: _.Dictionary<string>) => boolean;
+
+        result = _.findKey<string, {a: string;}>({a: ''}, predicateFn);
+        result = _.findKey<string, {a: string;}>({a: ''}, predicateFn, any);
+
+        result = _<{a: string;}>({a: ''}).findKey<string>(predicateFn);
+        result = _<{a: string;}>({a: ''}).findKey<string>(predicateFn, any);
+    }
 }
 
 result = <string>_.findLastKey({ 'a': 1, 'b': 2, 'c': 3, 'd': 4 }, function (num) {

lodash/lodash.d.ts

@@ -7104,6 +7104,15 @@ declare module _ {
          * @param thisArg The this binding of predicate.
          * @return Returns the key of the matched element, else undefined.
          */
+        findKey<TValues, TObject>(
+            object: TObject,
+            predicate?: DictionaryIterator<TValues, boolean>,
+            thisArg?: any
+        ): string;
+
+        /**
+         * @see _.findKey
+         */
         findKey<TObject>(
             object: TObject,
             predicate?: ObjectIterator<any, boolean>,
@@ -7129,6 +7138,14 @@ declare module _ {
     }
 
     interface LoDashObjectWrapper<T> {
+        /**
+         * @see _.findKey
+         */
+        findKey<TValues>(
+            predicate?: DictionaryIterator<TValues, boolean>,
+            thisArg?: any
+        ): string;
+
         /**
          * @see _.findKey
          */
@@ -8988,7 +9005,7 @@ declare module _ {
     }
 
     interface DictionaryIterator<T, TResult> {
-        (value: T, key: string, collection: Dictionary<T>): TResult;
+        (value: T, key?: string, collection?: Dictionary<T>): TResult;
     }
 
     interface ObjectIterator<T, TResult> {