Core: restore enumeration behavior in isPlainObject

Fixes gh-2968
Close gh-2970

diff --git a/src/core.js b/src/core.js
index b10128c7a7096f62a617dc46ebdc140f1cc8ca43..17673dfac3d36c920ac40a0643fad9b2c846abae 100644 (file)
--- a/src/core.js
+++ b/src/core.js
@@ -225,6 +225,7 @@ jQuery.extend( {
        },
 
        isPlainObject: function( obj ) {
+               var key;
 
                // Not plain objects:
                // - Any object or value whose internal [[Class]] property is not "[object Object]"
@@ -239,9 +240,11 @@ jQuery.extend( {
                        return false;
                }
 
-               // If the function hasn't returned already, we're confident that
-               // |obj| is a plain object, created by {} or constructed with new Object
-               return true;
+               // Own properties are enumerated firstly, so to speed up,
+               // if last one is own, then all properties are own
+               for ( key in obj ) {}
+
+               return key === undefined || hasOwn.call( obj, key );
        },
 
        isEmptyObject: function( obj ) {

diff --git a/test/unit/core.js b/test/unit/core.js
index 99b2acc452ca6f592fcbd6f8730140316a28e1df..d71539c028e927aff32937933fe9edd7fb57583e 100644 (file)
--- a/test/unit/core.js
+++ b/test/unit/core.js
@@ -286,13 +286,21 @@ QUnit.test( "type for `Symbol`", function( assert ) {
 });
 
 QUnit.asyncTest( "isPlainObject", function( assert ) {
-       assert.expect( 15 );
+       assert.expect( 19 );
 
-       var pass, iframe, doc,
+       var pass, iframe, doc, parentObj, childObj, deep,
                fn = function() {};
 
        // The use case that we want to match
        assert.ok( jQuery.isPlainObject( {} ), "{}" );
+       assert.ok( jQuery.isPlainObject( new window.Object() ), "new Object" );
+
+       parentObj = { foo: "bar" };
+       childObj = Object.create( parentObj );
+
+       assert.ok( !jQuery.isPlainObject( childObj ), "isPlainObject(Object.create({}))" );
+       childObj.bar = "foo";
+       assert.ok( !jQuery.isPlainObject( childObj ), "isPlainObject(Object.create({}))" );
 
        // Not objects shouldn't be matched
        assert.ok( !jQuery.isPlainObject( "" ), "string" );
@@ -320,6 +328,10 @@ QUnit.asyncTest( "isPlainObject", function( assert ) {
        // Again, instantiated objects shouldn't be matched
        assert.ok( !jQuery.isPlainObject( new fn() ), "new fn" );
 
+       // Deep object
+       deep = { "foo": { "baz": true }, "foo2": document };
+       assert.ok( jQuery.isPlainObject( deep ), "Object with objects is still plain" );
+
        // DOM Element
        assert.ok( !jQuery.isPlainObject( document.createElement( "div" ) ), "DOM Element" );