MACROMEDIA FLEX-FLEX ACTIONSCRIPT LANGUAGE Reference page 389

var speedWatcher:Function = function(prop, oldVal, newVal, speedLimit) {
// Check whether speed is above the limit
if (newVal > speedLimit) {
trace ("You are speeding.");
}
else {
trace ("You are not speeding.");
}
// Return the value of newVal.
return newVal;
}
// Use watch() to register the event handler, passing as parameters:
// - the name of the property to watch: "speed"
// - a reference to the callback function speedWatcher
// - the speedLimit of 55 as the userData parameter
myObject.watch("speed", speedWatcher, 55);
// set the speed property to 54, then to 57
myObject.speed = 54; // output: You are not speeding
myObject.speed = 57; // output: You are speeding
// unwatch the object
myObject.unwatch("speed");
myObject.speed = 54; // there should be no output
See also
Object.addProperty(), Object.unwatch()
Object.watch() 389