Core: Restore 1.x isPlainObject constructor checks

- Guard isPlainObject against inherited scalar constructors

Fixes gh-2982
Close gh-2985

diff --git a/src/core.js b/src/core.js
index 17673dfac3d36c920ac40a0643fad9b2c846abae..d2c0da0b66ea4a429bb107f653902f5d31cdde20 100644 (file)
--- a/src/core.js
+++ b/src/core.js
@@ -235,8 +235,10 @@ jQuery.extend( {
                        return false;
                }
 
+               // Not own constructor property must be Object
                if ( obj.constructor &&
-                               !hasOwn.call( obj.constructor.prototype, "isPrototypeOf" ) ) {
+                               !hasOwn.call( obj, "constructor" ) &&
+                               !hasOwn.call( obj.constructor.prototype || {}, "isPrototypeOf" ) ) {
                        return false;
                }
 

diff --git a/test/unit/core.js b/test/unit/core.js
index 2f4831828e30afb77a1c8c52f2785fc33e726099..7f58f489adb5a733ebda0f17085c208b5713eba9 100644 (file)
--- a/test/unit/core.js
+++ b/test/unit/core.js
@@ -286,7 +286,8 @@ QUnit.test( "type for `Symbol`", function( assert ) {
 });
 
 QUnit.asyncTest( "isPlainObject", function( assert ) {
-       assert.expect( 19 );
+
+       assert.expect( 22 );
 
        var pass, iframe, doc, parentObj, childObj, deep,
                fn = function() {};
@@ -294,6 +295,10 @@ QUnit.asyncTest( "isPlainObject", function( assert ) {
        // The use case that we want to match
        assert.ok( jQuery.isPlainObject( {} ), "{}" );
        assert.ok( jQuery.isPlainObject( new window.Object() ), "new Object" );
+       assert.ok( jQuery.isPlainObject( { constructor: fn } ),
+               "plain object with constructor property" );
+       assert.ok( jQuery.isPlainObject( { constructor: "foo" } ),
+               "plain object with primitive constructor property" );
 
        parentObj = { foo: "bar" };
        childObj = Object.create( parentObj );
@@ -328,6 +333,10 @@ QUnit.asyncTest( "isPlainObject", function( assert ) {
        // Again, instantiated objects shouldn't be matched
        assert.ok( !jQuery.isPlainObject( new fn() ), "new fn" );
 
+       // Instantiated objects with primitive constructors shouldn't be matched
+       fn.prototype.constructor = "foo";
+       assert.ok( !jQuery.isPlainObject( new fn() ), "new fn with primitive constructor" );
+
        // Deep object
        deep = { "foo": { "baz": true }, "foo2": document };
        assert.ok( jQuery.isPlainObject( deep ), "Object with objects is still plain" );