JavaScript Designing

Designing JavaScript applications often work best if you lay out the interface first. It is a way to decide not only the layout but the events for which you need to write code.

Once you have the design, then write the code that works for each event. It is a standard technique for event-driven programs.

JavaScript can be used to create several useful visual effects, including alternating color schemes, fades, scrolling marquees, and dynamic graphics.

Unlike effects created using other tools, JavaScript effects load quickly as part of your document, and can start even before a page is completely loaded.

There are two main frames of the message editor. The top frame displays the control panel. It is as wide as the browser allows and it has a fixed height sufficient to contain all of the controls.The top panel subdivided into a left and right section. The left just displays the last font color used. It is a fixed width. The right contains all of the controls and extends to the edge of the screen.

And the second frame will hold the text box where the message edited. Like the other frame, the width is the same as the screen. Its height is variable, taking up the remainder of the vertical space.

When JavaScript creates the objects from the framesets, all of the frames get "flattened." In other words, each frame, regardless of how deeply it is nested, is considered a child and is placed into the same frame array. All frames put into the array in the same sequence that they appear in the HTML file.

It makes it easier to refer to a property in another frame accurately. You don't need to know the relative relationship between frames since they are each a child of the parent.

If you are familiar with any object-oriented languages, you expect an object hierarchy to begin with a generic object from which all other objects are descendants or children. Unfortunately, the JavaScript object hierarchy does not follow this model.

It described as a system of ownership, and, even then, the analogy is not exact. For example, a window that creates another window could think of as the parent of the new window. However, if you try to refer to the original window from the child by saying parent.someobject, it will not work.

The Navigator is, in a way, the parent of all other JavaScript objects. It is the executable that runs the browser. The Navigator is responsible for the creation of all browser windows.

It is also responsible for responding to global window events. The Navigator is not a visual object. You cannot see it. You only interact with it through its visual construct: its windows.

Most Navigator window components manipulated in a yes/no fashion at the time of window creation. These include the menu, button bar, location display, status display, history list display, and scroll bars. At the time of window creation, you can determine whether the window resized as well as find its dimensions.

It might seem like a significant restriction. By rewriting the document, however, you can change the contents of a window. This technique enables you to modify the values of form elements, the content of the status bar, the position of the pointer in the history list, and the location at any time.