JavaScript: The Definitive Guide, Fourth Edition

Multiple Windows and Frames

Most of the client-side JavaScript examples we’ve seen so far have involved only a single window or frame. In the real world, JavaScript applications often involve multiple windows or frames. Recall that frames within a window are represented by Window objects; JavaScript makes little distinction between windows and frames. In the most interesting applications, there is JavaScript code that runs independently in each of several windows. The next section explains how the JavaScript code in each window can interact and cooperate with each of the other windows and with the scripts running in each of those windows.

Relationships Between Frames

We’ve already seen that the open( ) method of the Window object returns a new Window object representing the newly created window. We’ve also seen that this new window has an opener property that refers back to the original window. In this way, the two windows can refer to each other, and each can read properties and invoke methods of the other. The same thing is possible with frames. Any frame in a window can refer to any other frame through the use of the frames, parent, and top properties of the Window object.

Every window has a frames property. This property refers to an array of Window objects, each of which represents a frame contained within the window. (If a window does not have any frames, the frames[] array is empty and frames.length is zero.) Thus, a window (or frame) can refer to its first subframe as ...