From a9e681a82818bc92a512383caf060b4114a9eb97 Mon Sep 17 00:00:00 2001
From: ventuno <ventuno@users.noreply.github.com>
Date: Wed, 17 Aug 2016 17:20:36 -0700
Subject: [PATCH] Warn if using React.unmountComponentAtNode on a different
 React instance's tree. (#7456)

* Warn when using React.unmountComponentAtNode on a different React instance's tree

https://github.com/facebook/react/issues/3787

* Adding tests.

* Implementing recommended changes.

https://github.com/facebook/react/issues/3787
---
 src/renderers/dom/client/ReactMount.js        | 65 ++++++++++++++-----
 .../dom/client/__tests__/ReactMount-test.js   | 28 ++++++++
 2 files changed, 78 insertions(+), 15 deletions(-)

diff --git a/src/renderers/dom/client/ReactMount.js b/src/renderers/dom/client/ReactMount.js
index 5e1b2d8fabfdc..d7f24aaf386d0 100644
--- a/src/renderers/dom/client/ReactMount.js
+++ b/src/renderers/dom/client/ReactMount.js
@@ -207,6 +207,45 @@ function hasNonRootReactChild(container) {
   }
 }
 
+/**
+ * True if the supplied DOM node is a React DOM element and
+ * it has been rendered by another copy of React.
+ *
+ * @param {?DOMElement} node The candidate DOM node.
+ * @return {boolean} True if the DOM has been rendered by another copy of React
+ * @internal
+ */
+function nodeIsRenderedByOtherInstance(container) {
+  var rootEl = getReactRootElementInContainer(container);
+  return !!(rootEl && isReactNode(rootEl) && !ReactDOMComponentTree.getInstanceFromNode(rootEl));
+}
+
+/**
+ * True if the supplied DOM node is a valid node element.
+ *
+ * @param {?DOMElement} node The candidate DOM node.
+ * @return {boolean} True if the DOM is a valid DOM node.
+ * @internal
+ */
+function isValidContainer(node) {
+  return !!(node && (
+    node.nodeType === ELEMENT_NODE_TYPE ||
+    node.nodeType === DOC_NODE_TYPE ||
+    node.nodeType === DOCUMENT_FRAGMENT_NODE_TYPE
+  ));
+}
+
+/**
+ * True if the supplied DOM node is a valid React node element.
+ *
+ * @param {?DOMElement} node The candidate DOM node.
+ * @return {boolean} True if the DOM is a valid React DOM node.
+ * @internal
+ */
+function isReactNode(node) {
+  return isValidContainer(node) && (node.hasAttribute(ROOT_ATTR_NAME) || node.hasAttribute(ATTR_NAME));
+}
+
 function getHostRootInstanceInContainer(container) {
   var rootEl = getReactRootElementInContainer(container);
   var prevHostInstance =
@@ -330,11 +369,7 @@ var ReactMount = {
     );
 
     invariant(
-      container && (
-        container.nodeType === ELEMENT_NODE_TYPE ||
-        container.nodeType === DOC_NODE_TYPE ||
-        container.nodeType === DOCUMENT_FRAGMENT_NODE_TYPE
-      ),
+      isValidContainer(container),
       '_registerComponent(...): Target container is not a DOM element.'
     );
 
@@ -540,14 +575,18 @@ var ReactMount = {
     );
 
     invariant(
-      container && (
-        container.nodeType === ELEMENT_NODE_TYPE ||
-        container.nodeType === DOC_NODE_TYPE ||
-        container.nodeType === DOCUMENT_FRAGMENT_NODE_TYPE
-      ),
+      isValidContainer(container),
       'unmountComponentAtNode(...): Target container is not a DOM element.'
     );
 
+    if (__DEV__) {
+      warning(
+        !nodeIsRenderedByOtherInstance(container),
+        'unmountComponentAtNode(): The node you\'re attempting to unmount ' +
+        'was rendered by another copy of React.'
+      );
+    }
+
     var prevComponent = getTopLevelWrapperInContainer(container);
     if (!prevComponent) {
       // Check if the node being unmounted was rendered by React, but isn't a
@@ -593,11 +632,7 @@ var ReactMount = {
     transaction
   ) {
     invariant(
-      container && (
-        container.nodeType === ELEMENT_NODE_TYPE ||
-        container.nodeType === DOC_NODE_TYPE ||
-        container.nodeType === DOCUMENT_FRAGMENT_NODE_TYPE
-      ),
+      isValidContainer(container),
       'mountComponentIntoNode(...): Target container is not valid.'
     );
 
diff --git a/src/renderers/dom/client/__tests__/ReactMount-test.js b/src/renderers/dom/client/__tests__/ReactMount-test.js
index 3b79e8cc71ed2..ca7453d8d9439 100644
--- a/src/renderers/dom/client/__tests__/ReactMount-test.js
+++ b/src/renderers/dom/client/__tests__/ReactMount-test.js
@@ -229,6 +229,34 @@ describe('ReactMount', function() {
     );
   });
 
+  it('should warn if the unmounted node was rendered by another copy of React', function() {
+    jest.resetModuleRegistry();
+    var ReactDOMOther = require('ReactDOM');
+    var container = document.createElement('div');
+
+    class Component extends React.Component {
+      render() {
+        return <div><div /></div>;
+      }
+    }
+
+    ReactDOM.render(<Component />, container);
+    // Make sure ReactDOM and ReactDOMOther are different copies
+    expect(ReactDOM).not.toEqual(ReactDOMOther);
+
+    spyOn(console, 'error');
+    ReactDOMOther.unmountComponentAtNode(container);
+    expect(console.error.calls.count()).toBe(1);
+    expect(console.error.calls.argsFor(0)[0]).toBe(
+      'Warning: unmountComponentAtNode(): The node you\'re attempting to unmount ' +
+      'was rendered by another copy of React.'
+    );
+
+    // Don't throw a warning if the correct React copy unmounts the node
+    ReactDOM.unmountComponentAtNode(container);
+    expect(console.error.calls.count()).toBe(1);
+  });
+
   it('passes the correct callback context', function() {
     var container = document.createElement('div');
     var calls = 0;