I have discovered a problem in the isPlainObject of jQuery.

If I use as an argument of that function a simple variable like:{id:1,name:'wow'} i have an object with the .constructor initialized but without .constructor.prototype

This cause an exeception in Firefox 4.0.1 (Chrome and Safari are fine).

To handle it the library can be modified with a simple check.

The result is:

isPlainObject: function( obj ) {
		// Must be an Object.
		// Because of IE, we also have to check the presence of the constructor property.
		// Make sure that DOM nodes and window objects don't pass through, as well
		if ( !obj || jQuery.type(obj) !== "object" || obj.nodeType || jQuery.isWindow( obj ) ) {
			return false;
		}

		// Not own constructor property must be Object
		if ( obj.constructor &&
			!hasOwn.call(obj, "constructor") &&
//Changed code: added a check to dodge the exception 
			obj.constructor.prototype &&
//End of change
			!hasOwn.call(obj.constructor.prototype, "isPrototypeOf") ) {
			return false;
		}

		// Own properties are enumerated firstly, so to speed up,
		// if last one is own, then all properties are own.

		var key;
		for ( key in obj ) {}

		return key === undefined || hasOwn.call( obj, key );
	},