From 2a2de2efdc7bf549a8caf2b758866eb9d37f01ed Mon Sep 17 00:00:00 2001
From: John-David Dalton <john.david.dalton@gmail.com>
Date: Tue, 14 Oct 2014 20:36:13 -0700
Subject: [PATCH] Make `_.clone` and `_.cloneDeep` return an empty object for
 unsupported types.

---
 lodash.js    | 29 ++++++++++++++++++-----------
 test/test.js | 38 ++++++++++++++++++--------------------
 2 files changed, 36 insertions(+), 31 deletions(-)

diff --git a/lodash.js b/lodash.js
index 6eb999c03..aa6593eee 100644
--- a/lodash.js
+++ b/lodash.js
@@ -1500,7 +1500,10 @@
         result = initArrayClone(value, isDeep);
       } else if (isObject(value)) {
         result = initObjectClone(value, isDeep);
-        value = (isDeep && toString.call(result) == objectClass) ? value : result;
+        if (result === null) {
+          isDeep = false;
+          result = {};
+        }
       }
       if (!isDeep || result === value) {
         return result;
@@ -1521,11 +1524,15 @@
       stackB.push(result);
 
       // recursively populate clone (susceptible to call stack limits)
-      (isArr ? arrayEach : baseForOwn)(value, function(valValue, key) {
-        var valClone = customizer ? customizer(valValue, key) : undefined;
-        result[key] = typeof valClone == 'undefined'
-          ? baseClone(valValue, isDeep, null, stackA, stackB)
-          : valClone;
+      (isArr ? arrayEach : baseForOwn)(value, function(val, key) {
+        var computed = customizer ? customizer(val, key) : undefined,
+            useComputed = typeof computed != 'undefined',
+            isReflexive = useComputed && computed === computed;
+
+        if (useComputed && (isReflexive ? val === computed : val !== val)) {
+          return;
+        }
+        result[key] = useComputed ? computed : baseClone(val, isDeep, null, stackA, stackB);
       });
       return result;
     }
@@ -2927,9 +2934,9 @@
      * Initializes an array clone.
      *
      * @private
-     * @param {*} value The value to clone.
+     * @param {Array} array The array to clone.
      * @param {boolean} [isDeep=false] Specify a deep clone.
-     * @returns {*} Returns the initialized clone value.
+     * @returns {Array} Returns the initialized array clone.
      */
     function initArrayClone(array, isDeep) {
       var index = -1,
@@ -2953,14 +2960,14 @@
      * Initializes an object clone.
      *
      * @private
-     * @param {*} value The value to clone.
+     * @param {Object} object The object to clone.
      * @param {boolean} [isDeep=false] Specify a deep clone.
-     * @returns {*} Returns the initialized clone value.
+     * @returns {null|Object} Returns the initialized object clone.
      */
     function initObjectClone(object, isDeep) {
       var className = toString.call(object);
       if (!cloneableClasses[className] || isHostObject(object)) {
-        return object;
+        return null;
       }
       var Ctor = object.constructor,
           isArgs = className == argsClass || (!lodash.support.argsClass && isArguments(object)),
diff --git a/test/test.js b/test/test.js
index 10a342b2d..cf8598f88 100644
--- a/test/test.js
+++ b/test/test.js
@@ -1577,11 +1577,6 @@
     function Klass() { this.a = 1; }
     Klass.prototype = { 'b': 1 };
 
-    var nonCloneable = {
-      'DOM elements': body,
-      'functions': Klass
-    };
-
     var objects = {
       '`arguments` objects': arguments,
       'arrays': ['a', ''],
@@ -1603,6 +1598,15 @@
 
     objects['arrays'].length = 3;
 
+    var nonCloneable = {
+      'DOM elements': body,
+      'functions': Klass
+    };
+
+    _.each(errors, function(error) {
+      nonCloneable[error.name + 's'] = error;
+    });
+
     test('`_.clone` should perform a shallow clone', 2, function() {
       var expected = [{ 'a': 0 }, { 'b': 1 }],
           actual = _.clone(expected);
@@ -1652,13 +1656,7 @@
 
       _.forOwn(nonCloneable, function(object, key) {
         test('`_.' + methodName + '` should not clone ' + key, 1, function() {
-          strictEqual(func(object), object);
-        });
-      });
-
-      _.each(errors, function(error) {
-        test('`_.' + methodName + '` should not clone ' + error.name + ' objects', 1, function() {
-          strictEqual(func(error), error);
+          deepEqual(func(object), {});
         });
       });
 
@@ -1747,9 +1745,9 @@
         if (document) {
           var element = document.createElement('div');
           try {
-            strictEqual(func(element), element);
+            deepEqual(func(element), {});
           } catch(e) {
-            ok(false);
+            ok(false, e.message);
           }
         }
         else {
@@ -1855,7 +1853,7 @@
       try {
         strictEqual(combined(), undefined);
       } catch(e) {
-        ok(false);
+        ok(false, e.message);
       }
       notStrictEqual(combined, _.noop);
     });
@@ -2197,7 +2195,7 @@
           var callback = _.callback(value, {});
           strictEqual(callback(object), object);
         } catch(e) {
-          ok(false);
+          ok(false, e.message);
         }
       });
     });
@@ -4031,7 +4029,7 @@
             }
             deepEqual(actual, expected);
           } catch(e) {
-            ok(false);
+            ok(false, e.message);
           }
         });
       }
@@ -4516,7 +4514,7 @@
       try {
         deepEqual(func({ 'a': 1 }, undefined, { 'b': 2 }, null), { 'a': 1, 'b': 2 });
       } catch(e) {
-        ok(false);
+        ok(false, e.message);
       }
     });
 
@@ -6056,7 +6054,7 @@
         try {
           strictEqual(_.isEqual(element1, element2), false);
         } catch(e) {
-          ok(false);
+          ok(false, e.message);
         }
       }
       else {
@@ -10664,7 +10662,7 @@
         var data = { 'a': [1, 2, 3] };
         strictEqual(compiled(data), '123');
       } catch(e) {
-        ok(false);
+        ok(false, e.message);
       }
     });