Besides the full features Flex debugger, the trace() method is a useful way to inspect variables during debugging a Flex application: If you start a Flex application in Debug mode, trace() prints the value of the passed expression to consol.
Another way is to register a variable for permanent traceing. This way, the variable gets traced, each time it changes its value.
Based on the following TATRace component, you request tracing of a variable using a small piece of MXML. Suppose you’d like to trace a variable ‘traceableVariable’, then you just add [Bindable] in the line just before the declaration of the variable. This enables the variable to be referenced as ‘{traceableVariable}’.
Mark a variable as traceable
To trace each change of traceableVariable, add this element in your main MXML file