Checking for loaded data

Each function or method that loads data into a SWF file (except XMLSocket.send()) is asynchronous: the results of the action are returned at an indeterminate time.

Before you can use loaded data in a SWF file, you must check to see whether it has been loaded. For example, you can't load variables and manipulate their values in the same script because the data to manipulate doesn't exist in the file until it is loaded. In the following script, you cannot use the variable lastSiteVisited until you're sure that the variable has loaded from the file myData.txt. In the file myData.txt, you would have text similar to the following example:

lastSiteVisited=www.adobe.com

loadVariables("myData.txt", 0);
trace(lastSiteVisited); // undefined

Each function or method has a specific technique you can use to check data it has loaded. If you use loadVariables function or loadMovie function, you can load information into a movie clip target and use the onData handler to execute a script. If you use loadVariables function to load the data, the onData handler executes when the last variable is loaded. If you use loadMovie function to load the data, the onData handler executes each time a fragment of the SWF file is streamed into Flash Player.

For example, the following ActionScript loads the variables from the file myData.txt into the movie clip loadTarget_mc. An onData() handler assigned to the loadTarget_mc instance uses the variable lastSiteVisited, which is loaded from the file myData.txt. The following trace actions appear only after all the variables, including lastSiteVisited, are loaded:

this.createEmptyMovieClip("loadTarget_mc", this.getNextHighestDepth());
this.loadTarget_mc.onData = function() {
    trace("Data Loaded");
    trace(this.lastSiteVisited);
};
loadVariables("myData.txt", this.loadTarget_mc);

If you use the XML.load(), XML.sendAndLoad(), and XMLSocket.connect() methods, you should define a handler that processes the data when it arrives. This handler is a property of an XML or XMLSocket object to which you assign a function you defined. The handlers are called automatically when the information is received. For the XML object, use XML.onLoad() or XML.onData(). For the XMLSocket object, use XMLSocket.onConnect().