1. A method for providing, by a computing device, a runtime vulnerability defense for cross domain interactions for a Web application, the method comprising: creating a first iFrame object and a second iFrame object by the Web application, wherein the first and second iFrame objects belong to a lower domain; creating an object ◯ by the first iFrame object; sharing the created object ◯ by the second iFrame object; promoting, by a domain promotion module, the domain of the second iFrame object to an upper domain; creating, in the object ◯ that is shared, a source accessing function by the second iFrame object for submitting to a third party server a request to access the content of the third party server; and creating, in the object ◯ that is shared, a sanitization function by the first iFrame object for sanitizing the response received by the second iFrame object from the third party server, thereby providing runtime vulnerability defense for cross domain interactions.