Specifies the value of thisObject to be used within any function that ActionScript calls. This method also specifies the parameters to be passed to any called function. Because apply() is a method of the Function class, it is also a method of every Function object in ActionScript.

The parameters are specified as an Array object, unlike Function.call(), which specifies parameters as a comma-delimited list. This is often useful when the number of parameters to be passed is not known until the script actually executes.

Returns the value that the called function specifies as the return value.

Parameters

Related API Elements

Invokes the function represented by a Function object. Every function in ActionScript is represented by a Function object, so all functions support this method.

In almost all cases, the function call (()) operator can be used instead of this method. The function call operator produces code that is concise and readable. This method is primarily useful when the thisObject parameter of the function invocation needs to be explicitly controlled. Normally, if a function is invoked as a method of an object within the body of the function, thisObject is set to myObject, as shown in the following example:

  myObject.myMethod(1, 2, 3);
  

In some situations, you might want thisObject to point somewhere else; for example, if a function must be invoked as a method of an object, but is not actually stored as a method of that object:

  myObject.myMethod.call(myOtherObject, 1, 2, 3); 
  

You can pass the value null for the thisObject parameter to invoke a function as a regular function and not as a method of an object. For example, the following function invocations are equivalent:

  Math.sin(Math.PI / 4)
  Math.sin.call(null, Math.PI / 4)
  

Returns the value that the called function specifies as the return value.

Parameters

Related API Elements

The following example uses the

,

,

, and

classes to show various uses of functions in ActionScript. This is accomplished with the following steps:

1. The constructor for FunctionExample creates a local variable named simpleColl, which is populated with an array of integers ranging from 1 to 8.
2. The simpleColl object is printed using trace().
3. An EventListener object, listener, is added to simpleColl.
4. When the insert() and remove() functions are called, the listener responds to their events.
5. A second SimpleCollection object is created named greaterThanFourColl.
6. The greaterThanFourColl object is assigned the result of simpleColl.select() with the argument 4 and an anonymous function. The SimpleCollection object's select method is an internal iterator that uses the anonymous function parameter as a block.

package {
    import flash.display.Sprite;
    
    public class FunctionExample extends Sprite {
        public function FunctionExample() {
            var simpleColl:SimpleCollection;
            simpleColl = new SimpleCollection(0, 1, 2, 3, 4, 5, 6, 7, 8);
            trace(simpleColl);        // 0, 1, 2, 3, 4, 5, 6, 7, 8

            var listener:EventListener = new EventListener();
            simpleColl.addListener(listener);
            simpleColl.insert(9);        // itemInsertedHandler: 9
            simpleColl.remove(8);        // itemRemovedHandler: 8
            trace(simpleColl);        // 0, 1, 2, 3, 4, 5, 6, 7, 9

            var greaterThanFourColl:SimpleCollection;
            greaterThanFourColl = simpleColl.select(4, function(item:int, value:int){ return item > value });
            trace(greaterThanFourColl);    // 5, 6, 7, 9
        }
    }
}
    
import flash.display.Sprite;
    
class EventBroadcaster {
    private var listeners:Array;

    public function EventBroadcaster() {
        listeners = new Array();
    }
        
    public function addListener(obj:Object):void {
        removeListener(obj);
        listeners.push(obj);
    }
        
    public function removeListener(obj:Object):void {
        for(var i:uint = 0; i < listeners.length; i++) {
            if(listeners[i] == obj) {
                listeners.splice(i, 1);
            }
        }
    }
    
    public function broadcastEvent(evnt:String, ...args):void {
        for(var i:uint = 0; i < listeners.length; i++) {
            listeners[i][evnt].apply(listeners[i], args);
        }
    }    
}
    
class SimpleCollection extends EventBroadcaster {
    private var arr:Array;
        public function SimpleCollection(... args) {
        arr = (args.length == 1 && !isNaN(args[0])) ? new Array(args[0]) : args;
    }
        
    public function insert(obj:Object):void {
        remove(obj);
        arr.push(obj);
        broadcastEvent("itemInsertedHandler", obj);
    }
        
    public function remove(obj:Object):void {
        for(var i:uint = 0; i < arr.length; i++) {
            if(arr[i] == obj) {
                var obj:Object = arr.splice(i, 1)[0];
                broadcastEvent("itemRemovedHandler", obj);
            }
        }
    }

    public function select(val:int, fn:Function):SimpleCollection {
        var col:SimpleCollection = new SimpleCollection();
        for(var i:uint = 0; i < arr.length; i++) {
            if(fn.call(this, arr[i], val)) {
                col.insert(arr[i]);
            }
        }
        return col;
    }
        
    public function toString():String {
        var str:String = new String();
        for(var i:uint = 0; i < arr.length - 1; i++) {
            str += arr[i] + ", ";
        }
        str += arr[arr.length - 1];
        return str;
    }
}

class EventListener {
    public function EventListener() {
    }
    
    public function itemInsertedHandler(obj:Object):void {
        trace("itemInsertedHandler: " + obj);
    }
    
    public function itemRemovedHandler(obj:Object):void {
        trace("itemRemovedHandler: " + obj);        
    }
}