Align _.keys with ES6 and coerce primitives to objects.

dist/lodash.js

@@ -6799,14 +6799,16 @@
      * // => ['x', 'y'] (property order is not guaranteed across environments)
      */
     var keys = !nativeKeys ? shimKeys : function(object) {
-      var Ctor = object && object.constructor,
-          length = object ? object.length : 0;
+      object = Object(object);
+
+      var Ctor = object.constructor,
+          length = object.length;
 
       if ((Ctor && object === Ctor.prototype) ||
           (typeof length == 'number' && length > 0)) {
         return shimKeys(object);
       }
-      return isObject(object) ? nativeKeys(object) : [];
+      return nativeKeys(object);
     };
 
     /**
@@ -6830,9 +6832,8 @@
      * // => ['x', 'y', 'z'] (property order is not guaranteed across environments)
      */
     function keysIn(object) {
-      if (!isObject(object)) {
-        return [];
-      }
+      object = Object(object);
+
       var length = object.length;
       length = (typeof length == 'number' && length > 0 &&
         (isArray(object) || (support.nonEnumArgs && isArguments(object))) && length) >>> 0;
@@ -8461,10 +8462,8 @@
     lodash.map = map;
     lodash.mapValues = mapValues;
     lodash.matches = matches;
-    lodash.max = max;
     lodash.memoize = memoize;
     lodash.merge = merge;
-    lodash.min = min;
     lodash.mixin = mixin;
     lodash.negate = negate;
     lodash.omit = omit;
@@ -8559,6 +8558,8 @@
     lodash.isUndefined = isUndefined;
     lodash.kebabCase = kebabCase;
     lodash.lastIndexOf = lastIndexOf;
+    lodash.max = max;
+    lodash.min = min;
     lodash.noConflict = noConflict;
     lodash.noop = noop;
     lodash.now = now;

lodash.js

@@ -6990,15 +6990,17 @@
      * // => ['x', 'y'] (property order is not guaranteed across environments)
      */
     var keys = !nativeKeys ? shimKeys : function(object) {
-      var Ctor = object && object.constructor,
-          length = object ? object.length : 0;
+      object = Object(object);
+
+      var Ctor = object.constructor,
+          length = object.length;
 
       if ((Ctor && object === Ctor.prototype) ||
           (typeof length == 'number' && length > 0) ||
           (support.enumPrototypes && typeof object == 'function')) {
         return shimKeys(object);
       }
-      return isObject(object) ? nativeKeys(object) : [];
+      return nativeKeys(object);
     };
 
     /**
@@ -7022,9 +7024,8 @@
      * // => ['x', 'y', 'z'] (property order is not guaranteed across environments)
      */
     function keysIn(object) {
-      if (!isObject(object)) {
-        return [];
-      }
+      object = Object(object);
+
       var length = object.length;
       length = (typeof length == 'number' && length > 0 &&
         (isArray(object) || (support.nonEnumStrings && isString(object)) ||

test/test.js

@@ -5721,6 +5721,11 @@
       deepEqual(actual.sort(), ['a', 'b']);
     });
 
+    test('`_.' + methodName + '` should coerce primitives to objects', 1, function() {
+      var actual = func('abc');
+      deepEqual(actual.sort(), ['0', '1', '2']);
+    });
+
     test('`_.' + methodName + '` should treat sparse arrays as dense', 1, function() {
       var array = [1];
       array[2] = 3;
@@ -5729,7 +5734,7 @@
       deepEqual(actual.sort(), ['0', '1', '2']);
     });
 
-    test('`_.' + methodName + '` should custom properties on arrays', 1, function() {
+    test('`_.' + methodName + '` should return keys for custom properties on arrays', 1, function() {
       var array = [1];
       array.a = 1;
 
@@ -5755,7 +5760,7 @@
       }
     });
 
-    test('`_.' + methodName + '` should custom properties on `arguments` objects', 1, function() {
+    test('`_.' + methodName + '` should return keys for custom properties on `arguments` objects', 1, function() {
       if (!(isPhantom || isStrict)) {
         args.a = 1;
         var actual = func(args);
@@ -5785,7 +5790,7 @@
       deepEqual(actual.sort(), ['0', '1', '2']);
     });
 
-    test('`_.' + methodName + '` should custom properties on string objects', 1, function() {
+    test('`_.' + methodName + '` should return keys for custom properties on string objects', 1, function() {
       var object = Object('a');
       object.a = 1;
 

test/underscore.html

@@ -110,7 +110,8 @@
 						'Died on test #63'
 					],
 					'keys': [
-						'is not fooled by sparse arrays; see issue #95'
+						'is not fooled by sparse arrays; see issue #95',
+						'[]'
 					],
 					'omit': [
 						'can accept a predicate'