darron schall :: application developer specializing in the flash platform

Did you know ActionScript 3 introduced a new loop construct? I discovered this while doing a lot of XML manipulation with E4X, and it's really a gem.

Along with the "for..in" loop, we now have at our disposal a "for each..in" loop. The two loops are very similar in style/syntax, but there's a subtle difference. Consider the following code snippet:

var arr:Array = ["test", "test2", "test3"];
			
// Use a regular for in loop to access the properties in arr
for ( var i in arr ) {
 	trace( i );	
}
			
// Use the new for each in loop to access the values in arr
for each ( var s:String in arr ) {
 	trace( s );	
}

The first loop will trace values 0, 1, and 2. The for..in loop will loop over the property names in an object - in this case, we get the array indexes. In order to get the values in the array, we would have to "trace( arr[i] )".

The second loop will trace values test, test2, and test3. Notice the subtle difference here? Instead of getting the properties in an object, we get the property values. This is a handy shortcut, and is especially useful in dealing with XML in the E4X manner:

var data:XML = <model>
		<foo>12</foo>
		<foo>61</foo>
		<foo>hello</foo>
	</model>;
					
for each ( var f:XML in data.foo ) {
 	trace( f );	
}

The above loop will out 12, 61, and hello.

Nothing earth shattering really, just something new to add to your bag of tricks... Enjoy!