AS3 has always had great support for XML built right into the language, but how fast is it? Today’s article compares the performance of operators that work on XML objects like .@x, .x, ..x, and ["x"] against their equivalents in plain Object instances and typed class instances. Just how slow are the XML operators? Read on to find out.
Posts Tagged dot
The Flash API has a gem of a class in Proxy. You can use it to customize the behavior of the dot (.), index ([]), delete, and in operators as well as the for-in and for-each-in loops. Today’s article answers a recent comment by exploring the performance implications of all this fancy customizing that Proxy allows.
One of the very nice features of AS3 (and AS2 and JavaScript for that matter) is that you can dynamically access the fields of any object. This leads to much more dynamic code since you no longer need to know what field to access at compile time. As we’ve often seen with other dynamic features, this can come at a steep cost in terms of performance. Today we’ll see just how slow accessing fields this way is to get a good idea of just how much performance we give up when using this feature.
There are three main ways to access the contents of objects in AS3: the dot (.) operator, the index ([]) operator, and the in operator. The first two are well known and functionally-equivalent because obj.property evaluates to the same value as obj["property"]. The in operator is different as I’ve described before: it returns a Boolean indicating whether or not the object has the given property. There are a lot of cases—error checking, for example—where we only care if an object has a property and not what that property is. So, can we improve performance by using the is operator rather than the index or dot operators? (UPDATE: hasOwnProperty results added)