This API lets websites interact with a user agent’s password system so that websites can deal in a uniform way with site credentials and user agents can provide better assistance with the management of their credentials. For example, user agents have a particularly hard time dealing with federated identity providers or esoteric sign-in mechanisms that use more than just a username and password. To address these problems, the Credential Management API provides ways for a website to store and retrieve different types of password credentials. This give users capabilities such as seeing the federated account they used to sign on to a site, or resuming a session without the explicit sign-in flow of an expired session.
Window.outerHeight gets the height in pixels of the whole browser window. It represents the height of the whole browser window including sidebar (if expanded), window chrome and window resizing borders/handles.