fix(utils/clone): don't try to clone elements from different window context

lib/core/utils/clone.js

@@ -5,13 +5,7 @@ import cache from '../base/cache';
  * @param  {Mixed} obj The object/array to clone
  * @return {Mixed} A clone of the initial object or array
  */
-export default function clone(obj) {
-  // handle circular references by caching the cloned object and returning it
-  const seen = cache.get('utils.clone', () => new WeakMap());
-  if (seen.has(obj)) {
-    return seen.get(obj);
-  }
-
+export default function clone(obj, recursed) {
   if (obj === null || typeof obj !== 'object') {
     return obj;
   }
@@ -26,11 +20,23 @@ export default function clone(obj) {
     return obj;
   }
 
+  // handle circular references by caching the cloned object and returning it
+  // clear for every new call to clone so we don't return a cached value for
+  // a different object
+  const seen = cache.get('utils.clone', () => new Map());
+  if (!recursed) {
+    seen.clear();
+  }
+
+  if (recursed && seen.has(obj)) {
+    return seen.get(obj);
+  }
+
   if (Array.isArray(obj)) {
     const out = [];
     seen.set(obj, out);
     obj.forEach(value => {
-      out.push(clone(value));
+      out.push(clone(value, true));
     });
     return out;
   }
@@ -39,7 +45,7 @@ export default function clone(obj) {
   seen.set(obj, out);
   // eslint-disable-next-line guard-for-in
   for (const key in obj) {
-    out[key] = clone(obj[key]);
+    out[key] = clone(obj[key], true);
   }
   return out;
 }

test/core/utils/clone.js

@@ -96,7 +96,7 @@ describe('utils.clone', () => {
     assert.deepEqual(Cat.prototype.meow, c.meow);
   });
 
-  it('should clone circular objects', () => {
+  it('should clone circular objects while keeping the circular reference', () => {
     const obj = { cats: true };
     obj.child = obj;
     const c = clone(obj);
@@ -107,6 +107,26 @@ describe('utils.clone', () => {
       cats: true,
       child: c
     });
+    assert.strictEqual(c, c.child);
+  });
+
+  it('should not return the same object when cloned twice', () => {
+    const obj = { cats: true };
+    const c1 = clone(obj);
+    const c2 = clone(obj);
+
+    assert.notStrictEqual(c1, c2);
+  });
+
+  it('should not return the same object when nested', () => {
+    const obj = { dogs: true };
+    const obj1 = { cats: true, child: { prop: obj } };
+    const obj2 = { fish: [0, 1, 2], child: { prop: obj } };
+
+    const c1 = clone(obj1);
+    const c2 = clone(obj2);
+
+    assert.notStrictEqual(c1.child.prop, c2.child.prop);
   });
 
   it('should not clone HTML elements', () => {
@@ -119,7 +139,7 @@ describe('utils.clone', () => {
     obj.cats = false;
 
     assert.equal(c.cats, true);
-    assert.equal(c.node, obj.node);
+    assert.strictEqual(c.node, obj.node);
   });
 
   it('should not clone HTML elements from different windows', () => {
@@ -135,6 +155,6 @@ describe('utils.clone', () => {
     obj.cats = false;
 
     assert.equal(c.cats, true);
-    assert.equal(c.node, obj.node);
+    assert.strictEqual(c.node, obj.node);
   });
 });