Adding ActionScript to Multiple Instances

I wrote a small snippet of ActionScript 2.0 the other day that I was quite proud of. It actually isn’t a very complicated block of code, but I was having trouble making a movieclip do what I wanted so I was quite pleased when I finally got it to work.

Here was my problem:

I had a movieclip, twenty-four frames long, with twenty-three buttons inside. When the mouse moved over each button, the movieclip was supposed to go to a different frame. I didn’t want to code each button individually because that can be tedious, so I employed a method I have often used to add the same code to multiple buttons. First I gave the timeline a name by assigning it to a variable:

var menus:MovieClip = this;

My buttons inside the movieclip were named btn1 through btn23, so I then created a for statement like so:

for (var i=1; i< =23; i++) {
    t = menus[“btn”+i];
    t.onRollOver = function() {
        gotoAndStop(i+1);
    }
    t.onRollOut = function() {
        gotoAndStop(1);
    }
}

Using the temporary variables t and i, I was able to assign onRollOver and onRollOut functions to each button. The code actually worked really well when the mouse rolled off the buttons, but when the mouse rolled over the buttons, the movieclip always went to Frame 24 (23 + 1), no matter which button it was over. Obviously, this wasn’t going to work.

I tried several things to make the code work, and had no luck. For some reason, whenever I used the i variable in referencing the frame to go to, it only registered as being equal to 23. I had to figure out a way to capture the value of i at each iteration. Then it occured to me. Since i wasn’t working, maybe I could reference the object directly, using the instance name to tell the movieclip which frame to go to. That was easy enough to do using this._name, but I still had the problem of getting rid of the btn part of the instance names. That was when I remembered substring. I rewrote my code to convert the substring of each instance name to an integer, added 1, and it worked perfectly. My code now looked like this:

var menus:MovieClip = this;

for (var i=1; i < =23; i++) {
    t = menus[“btn”+i];
    t.onRollOver = function() {
        gotoAndStop(int(substring(this._name, 4, this._name.length)) + 1);
    }
    t.onRollOut = function() {
        gotoAndStop(1);
    }
}