338 Part II: Developing an Ajax Library^
pulse a logo both in the upper corner of the window and on a tab, set status bar messages,
fill in a thermometer like progress meter, and change the cursor. Add to this the incremental
page paint and there are as many as six different indications of activity going on during a
traditional page load.
The developer’s responsibility for showing activity was fairly limited in the past. As
long as the developer made sure to code their pages for incremental loading so that images
and other objects appeared on the screen every few moments, the browser took care of the
rest for reasonable delays. However, in the case of long downloads or slow data queries,
developers may have resorted to loading screens that ranged from simple animated GIFs
to more complicated screens showing the status of various components being loaded.
Figure 8-2 shows a few examples of such loading screens.FIGURE 8-1 Browser’s provide numerous activity indications