[as3]
import flash.system.Capabilities;

if (ExternalInterface.available){
trace("ExternalInterface available")
if(flash.system.Capabilities.playerType!="StandAlone" && flash.system.Capabilities.playerType!="External"){
trace("Browser mode, playerType: " + flash.system.Capabilities.playerType);
strCurSlide = ExternalInterface.call("getFlashTemplate_curSlideID");
//run a function
} else {
trace("Standalone/Flash Debugging mode, playerType: " + flash.system.Capabilities.playerType);
//run a different function
}
} else {
trace("ExternalInterface no available")
//run a different function();
}

[/as3]

Complete list here