ProtractorJs is an end-to-end framework written for AngularJS applications. It uses Selenium WebDriver features internally. The main advantage of the regular WebDriver test is an ability to cooperate well with SPA application. The main problem with this type of systems is asynchronization. Single Page Applications change their look without reloading the whole page. So it is very hard to determine when the application is ready for action. Fortunately, Protractor knows the Angular internal mechanisms, so he is aware when application finish all operations.