we’ve looked at so far cause the
interpreter to repeatedly execute blocks of code. Most of your loops
will be of this “ActionScript-statement” type. But
it’s also sometimes desirable to create a
loop by looping Flash’s playhead in the timeline. To
do so, attach a series of statements to any frame; on the next frame,
gotoAndPlay( ) function whose
destination is the previous frame. When the movie plays, the playhead
will cycle between the two frames, causing the code on the first
frame to be executed repeatedly.
We can make a simple timeline loop by following these steps:
Start a new Flash movie.
On frame 1, attach the following statement:
trace("Hi there! Welcome to frame 1");
On frame 2, attach the following statements:
trace("This is frame 2"); gotoAndPlay(1);
Select Control → Test Movie.
When we test our movie, we see an endless stream of the following text:
Hi there! Welcome to frame 1 This is frame 2 Hi there! Welcome to frame 1 This is frame 2
Timeline loops can do two things ordinary loops cannot:
They can execute a block of code an infinite number of times without causing an error.
They can execute a block of code that requires a Stage update between loop iterations.
This second feature of timeline loops requires a little more explanation. When any frame’s script is executed, the movie Stage is not updated visually until the end of the script. This means that traditional loop statements cannot be used to perform repetitive ...