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

src/renderers/dom/client/ReactMount.js

@@ -206,6 +206,45 @@ function hasNonRootReactChild(container) {
   }
 }
 
+/**
+ * True if the supplied DOM node is a React DOM element and
+ * it has been rendered by a different React instance.
+ *
+ * @param {?DOMElement} node The candidate DOM node.
+ * @return {boolean} True if the DOM has been rendered by a different React instance
+ * @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 isNodeElement(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 isNodeElement(node) && (node.hasAttribute(ROOT_ATTR_NAME) || node.hasAttribute(ATTR_NAME));
+}
+
 function getHostRootInstanceInContainer(container) {
   var rootEl = getReactRootElementInContainer(container);
   var prevHostInstance =
@@ -329,11 +368,7 @@ var ReactMount = {
     );
 
     invariant(
-      container && (
-        container.nodeType === ELEMENT_NODE_TYPE ||
-        container.nodeType === DOC_NODE_TYPE ||
-        container.nodeType === DOCUMENT_FRAGMENT_NODE_TYPE
-      ),
+      isNodeElement(container),
       '_registerComponent(...): Target container is not a DOM element.'
     );
 
@@ -546,14 +581,18 @@ var ReactMount = {
     );
 
     invariant(
-      container && (
-        container.nodeType === ELEMENT_NODE_TYPE ||
-        container.nodeType === DOC_NODE_TYPE ||
-        container.nodeType === DOCUMENT_FRAGMENT_NODE_TYPE
-      ),
+      isNodeElement(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 React instance.'
+      );
+    }
+
     var prevComponent = getTopLevelWrapperInContainer(container);
     if (!prevComponent) {
       // Check if the node being unmounted was rendered by React, but isn't a
@@ -599,11 +638,7 @@ var ReactMount = {
     transaction
   ) {
     invariant(
-      container && (
-        container.nodeType === ELEMENT_NODE_TYPE ||
-        container.nodeType === DOC_NODE_TYPE ||
-        container.nodeType === DOCUMENT_FRAGMENT_NODE_TYPE
-      ),
+      isNodeElement(container),
       'mountComponentIntoNode(...): Target container is not valid.'
     );
 

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 instance', function() {
+    jest.resetModuleRegistry();
+    var ReactDOMOther = require('ReactDOM');
+    var container = document.createElement('container');
+
+    class Component extends React.Component {
+      render() {
+        return <div><div /></div>;
+      }
+    }
+
+    ReactDOM.render(<Component />, container);
+    // Make sure ReactDOM and ReactDOMOther are different instances
+    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 React instance.'
+    );
+
+    // Don't throw a warning if the correct React instance 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;