Changes

The JavaScript ''window object'' sits at the top of the JavaScript Object hierarchy and represents the browser window (or windows if you have more than one browser window open at any one time). Up until this chapter we have focused on the internals and syntax of JavaScript. In this chapter we will begin to make things happen on the screen (which, after all, is one of the main purposes of JavaScript). The window object allows developers to perform tasks such as opening and closing browser windows, displaying alert and prompt dialogs and set up timeouts (specifying an action to take place after a specified period of time). Although Timeouts are a feature of the window object we will cover them in the [[JavaScript Timeouts]] chapter, rather than in this chapter.