Not override props with undefined in cloneElement

facebook · Feb 8, 2016 · 190950f · 190950f
1 parent 725a723
commit 190950f
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Showing 2 changed files with 21 additions and 1 deletion.
diff --git a/src/isomorphic/classic/element/ReactElement.js b/src/isomorphic/classic/element/ReactElement.js
@@ -245,7 +245,8 @@ ReactElement.cloneElement = function(element, config, children) {
     // Remaining properties override existing props
     for (propName in config) {
       if (config.hasOwnProperty(propName) &&
-          !RESERVED_PROPS.hasOwnProperty(propName)) {
+          !RESERVED_PROPS.hasOwnProperty(propName) &&
+          config[propName] !== undefined) {
         props[propName] = config[propName];
       }
     }

diff --git a/src/isomorphic/classic/element/__tests__/ReactElement-test.js b/src/isomorphic/classic/element/__tests__/ReactElement-test.js
@@ -273,6 +273,25 @@ describe('ReactElement', function() {
     expect(inst2.props.prop).toBe(null);
   });
 
+  it('does not override props for undefined config key in cloning', function() {
+    var Component = React.createClass({
+      getDefaultProps: function() {
+        return {prop: 'testKey'};
+      },
+      render: function() {
+        return React.createElement('span', null, this.props.prop);
+      },
+    });
+    var instance = React.createElement(Component);
+
+    var clonedInstance = React.cloneElement(instance, {prop: undefined});
+    expect(clonedInstance.props.prop).toBe('testKey');
+
+    // Still override for null value
+    var clonedInstance2 = React.cloneElement(instance, {prop: null});
+    expect(clonedInstance2.props.prop).toBe(null);
+  });
+
   it('throws when changing a prop (in dev) after element creation', function() {
     var Outer = React.createClass({
       render: function() {