Remove support for cloning arrays and make _.isEqual more robust when comparing errors.

lodash.js

@@ -162,16 +162,16 @@
 
   /** Used to identify object classifications that `_.clone` supports */
   var cloneableClasses = {};
-  cloneableClasses[argsClass] =
-  cloneableClasses[arrayClass] = cloneableClasses[arrayBufferClass] =
-  cloneableClasses[boolClass] = cloneableClasses[dateClass] =
-  cloneableClasses[errorClass] = cloneableClasses[float32Class] =
+  cloneableClasses[argsClass] = cloneableClasses[arrayClass] =
+  cloneableClasses[arrayBufferClass] = cloneableClasses[boolClass] =
+  cloneableClasses[dateClass] = cloneableClasses[float32Class] =
   cloneableClasses[float64Class] = cloneableClasses[int8Class] =
   cloneableClasses[int16Class] = cloneableClasses[int32Class] =
   cloneableClasses[numberClass] = cloneableClasses[objectClass] =
   cloneableClasses[regexpClass] = cloneableClasses[stringClass] =
   cloneableClasses[uint8Class] = cloneableClasses[uint8ClampedClass] =
   cloneableClasses[uint16Class] = cloneableClasses[uint32Class] = true;
+  cloneableClasses[errorClass] =
   cloneableClasses[funcClass] = cloneableClasses[mapClass] =
   cloneableClasses[setClass] = cloneableClasses[weakMapClass] = false;
 
@@ -1237,9 +1237,6 @@
           case dateClass:
             return new Ctor(+value);
 
-          case errorClass:
-            return new Ctor(value.message);
-
           case float32Class: case float64Class:
           case int8Class: case int16Class: case int32Class:
           case uint8Class: case uint8ClampedClass: case uint16Class: case uint32Class:
@@ -1791,10 +1788,6 @@
           // to `1` or `0` treating invalid dates coerced to `NaN` as not equal
           return +value == +other;
 
-        case errorClass:
-          // check properties instead of coercing to strings to support IE < 8
-          return value.name === other.name && value.message === other.message;
-
         case numberClass:
           // treat `NaN` vs. `NaN` as equal
           return (value != +value)
@@ -1804,18 +1797,20 @@
 
         case regexpClass:
         case stringClass:
-          // coerce regexes to strings (http://es5.github.io/#x15.10.6.4)
-          // treat string primitives and object instances as equal
+          // coerce regexes to strings (http://es5.github.io/#x15.10.6.4) and
+          // treat strings primitives and string objects as equal
           return value == String(other);
       }
+      var isArr = arrayLikeClasses[valClass],
+          isErr = valClass == errorClass;
+
       if (!support.argsClass) {
         valIsArg = isArguments(value);
         othIsArg = isArguments(other);
       }
-      var isArr = arrayLikeClasses[valClass];
       if (!isArr) {
-        // exit for functions and DOM nodes
-        if (valClass != objectClass || (!support.nodeClass && (isNode(value) || isNode(other)))) {
+        // exit for things like functions and DOM nodes
+        if (!(isErr || valClass == objectClass) || (!support.nodeClass && (isNode(value) || isNode(other)))) {
           return false;
         }
         // unwrap any `lodash` wrapped values
@@ -1836,6 +1831,10 @@
           var valCtor = valIsArg ? Object : value.constructor,
               othCtor = othIsArg ? Object : other.constructor;
 
+          // error objects of different types are not equal
+          if (isErr && valCtor.prototype.name != othCtor.prototype.name) {
+            return false;
+          }
           // non `Object` object instances with different constructors are not equal
           if (valCtor != othCtor &&
                 !(isFunction(valCtor) && valCtor instanceof valCtor && isFunction(othCtor) && othCtor instanceof othCtor) &&
@@ -1895,8 +1894,8 @@
         }
       }
       else {
-        var valProps = keys(value),
-            othProps = keys(other);
+        var valProps = isErr ? ['message', 'name'] : keys(value),
+            othProps = isErr ? ['message', 'name'] : keys(other);
 
         if (valIsArg) {
           valProps.push('length');
@@ -1910,7 +1909,8 @@
         if (result || isWhere) {
           while (++index < length) {
             var key = valProps[index];
-            result = hasOwnProperty.call(other, key);
+            result = isErr || hasOwnProperty.call(other, key);
+
             if (result) {
               valValue = value[key];
               othValue = other[key];

test/test.js

@@ -1241,30 +1241,30 @@
     Klass.prototype = { 'b': 1 };
 
     var nonCloneable = {
-      'a DOM element': body,
-      'a function': Klass
+      'DOM elements': body,
+      'functions': Klass
     };
 
     var objects = {
-      'an `arguments` object': arguments,
-      'an array': ['a', ''],
-      'an array-like-object': { '0': 'a', '1': '', 'length': 3 },
-      'boolean': false,
-      'boolean object': Object(false),
-      'a Klass instance': new Klass,
-      'an object': { 'a': 0, 'b': 1, 'c': 3 },
-      'an object with object values': { 'a': /a/, 'b': ['B'], 'c': { 'C': 1 } },
-      'an object from another document': _._object || {},
-      'null': null,
-      'a number': 3,
-      'a number object': Object(3),
-      'a regexp': /a/gim,
-      'a string': 'a',
-      'a string object': Object('a'),
-      'undefined': undefined
+      '`arguments` objects': arguments,
+      'arrays': ['a', ''],
+      'array-like-objects': { '0': 'a', '1': '', 'length': 3 },
+      'booleans': false,
+      'boolean objects': Object(false),
+      'Klass instances': new Klass,
+      'objects': { 'a': 0, 'b': 1, 'c': 3 },
+      'objects with object values': { 'a': /a/, 'b': ['B'], 'c': { 'C': 1 } },
+      'objects from another document': _._object || {},
+      'null values': null,
+      'numbers': 3,
+      'number objects': Object(3),
+      'regexes': /a/gim,
+      'strings': 'a',
+      'string objects': Object('a'),
+      'undefined values': undefined
     };
 
-    objects['an array'].length = 3;
+    objects['arrays'].length = 3;
 
     test('`_.clone` should shallow clone by default', 2, function() {
       var expected = [{ 'a': 0 }, { 'b': 1 }],
@@ -1313,13 +1313,9 @@
       });
 
       _.each(errorTypes, function(type) {
-        test('`_.' + methodName + '` should clone ' + type + ' objects', 2, function() {
-          var Ctor = root[type],
-              error = new Ctor('text'),
-              actual = func(error);
-
-          ok(_.isEqual(actual, error));
-          notStrictEqual(actual, error);
+        test('`_.' + methodName + '` should not clone ' + type + ' objects', 1, function() {
+          var error = new root[type];
+          strictEqual(func(error), error);
         });
       });
 
@@ -1426,7 +1422,7 @@
 
       test('`_.' + methodName + '` should return a unwrapped value when chaining', 2, function() {
         if (!isNpm) {
-          var object = objects['an object'],
+          var object = objects['objects'],
               actual = _(object)[methodName]();
 
           deepEqual(actual, object);