Is there a "when" in programming as oppose to if/else if etc?

what i mean is, is there a way in AS3, or in programming in general(php, js etc) to make an event fire/activate “WHEN” something does something, as oppose to an if/else if / else statements ?

for example, say i want to make an event fire /activate ***ONLY ******when ***a frame label is hit, and thereafter , do something else etc, essentially making it do things one by one down the line according to ***WHEN ***certain objectives are met. is there a “when” type of statement etc that will do this as oppose to if/else if etc???

for example, using the above example, instead of me doing something like this:

xyz.addEventListener(Event.ENTER_FRAME / or INIT , btn);

function btn(e:Event):void{
    ***if*** ( externalSwf.currentFrameLabel == " label here "){
          do something code here.
    }

}

is there a way to do it like this:

xyz.addEventListener(Event.ENTER_FRAME / or INIT , btn);

function btn(e:Event):void{
    ***when*** ( externalSwf.currentFrameLabel == " label here "){
          do this.
       

          when (this happens){ 
        do this next
}
    }

}

etc…

how can one accomplish that?

reason i ask is because i have a little project im working on (smooth transitions of external swfs code) that is partly working but i cant for the life of me, figure out how to implement a structure like what i have directly above.

hope its not confusing.

any tips ideas etc i gladly appreciate.

thank you.