====== Getting Return Values from Function Calls ======

{{tag>flashjs tutorial javascript}}

This page shows a simple example of how to get return values from JavaScript when calling a JavaScript function from Flash.

The same technique works when getting return values from Flash when calling a Flash function from JavaScript, but you just reverse the function order.

<code actionscript>
//import proxy class
import com.macromedia.javascript.JavaScriptProxy;

class MyClass
{
    private var proxy:JavaScriptProxy;
    
    function MyClass()
    {
        //create instance of proxy to JavaScript, pass in args, since
        //we will receive calls from JS
        proxy = new JavaScriptProxy(_root.lcId, this);
        
        sayHello();
    }
    
    //Calls JavaScript sayHello function
    function sayHello():Void
    {
        proxy.call("sayHello", "Homer");
    }
    
    //This gets called when a value is returned from the sayHello function in
    //JavaScript
    function sayHelloReturn(result:String):Void
    {
        trace("Returned from JavaScript : " + result); //traces 'Hello Homer !'
    }
}</code>


HTML / JavaScript Code
<code javascript><script type="text/javascript" src="/path/to/Exception.js"></script>
<script type="text/javascript" src="/path/to/FlashTag.js"></script>
<script type="text/javascript" src="/path/to/FlashSerializer.js"></script>
<script type="text/javascript" src="/path/to/FlashProxy.js"></script>

<script language="JavaScript">

    //create unique id
    var uid = new Date().getTime();
    
    //create proxy to flash
    var flashProxy = new FlashProxy(uid, '/path/to/JavaScriptFlashGateway.swf');
    
    //this function is called from Flash
    function sayHello(n)
    {
        var returnString = "Hello " + n + "!";
        flashProxy.call("sayHelloReturn", returnString);
    }
    
</script>

<script type="text/javascript">
    var tag = new FlashTag('/path/to/flashContent.swf', 300, 300); // last two arguments are height and width
    tag.setFlashvars('lcId='+uid);
    tag.write(document);
</script></code>

----
You can also make the return function dynamic, like this:

ActionScript code
<code javascript>
//import proxy class
import com.macromedia.javascript.JavaScriptProxy;

class MyClass
{
    private var proxy:JavaScriptProxy;
    
    function MyClass()
    {
        //create instance of proxy to JavaScript, pass in args, since
        //we will receive calls from JS
        proxy = new JavaScriptProxy(_root.lcId, this);
    }
    
    function echo(callBack:String, result:String):Void
    {
        proxy.call(callBack, result);        
    }
}</code>


HTML / JavaScript Code
<code javascript>
<script type="text/javascript" src="/path/to/Exception.js"></script>
<script type="text/javascript" src="/path/to/FlashTag.js"></script>
<script type="text/javascript" src="/path/to/FlashSerializer.js"></script>
<script type="text/javascript" src="/path/to/FlashProxy.js"></script>

<script language="JavaScript">

    //create unique id
    var uid = new Date().getTime();
    
    //create proxy to flash
    var flashProxy = new FlashProxy(uid, '/path/to/JavaScriptFlashGateway.swf');
    
    //this function is called from Flash
    function sayHello(n)
    {
        var returnString = "Hello " + n + "!";
        alert(n);
    }

    flashProxy.call("echo", "sayHello", "hello");    
</script>

<script type="text/javascript">
    var tag = new FlashTag('/path/to/flashContent.swf', 300, 300); // last two arguments are height and width
    tag.setFlashvars('lcId='+uid);
    tag.write(document);
</script></code>

----

Of course, in the ActionScript code, you could handle the return function in a number of ways, such as broadcasting an event when the value is returned like so:

ActionScript Code
<code actionscript>//import proxy class
import com.macromedia.javascript.JavaScriptProxy;
import mx.events.EventDispatcher;

class MyClass
{
    private var proxy:JavaScriptProxy;
    
    //declare EventDispatcher functions
    private var dispatchEvent:Function;
    public var addEventListener:Function;
    public var removeEventListener:Function;	
    
    function MyClass()
    {
        //initialize class to dispatch events
        mx.events.EventDispatcher.initialize(this);
        
        //create instance of proxy to JavaScript, pass in args, since
        //we will receive calls from JS
        proxy = new JavaScriptProxy(_root.lcId, this);
        
        sayHello();
    }
    
    //Calls JavaScript sayHello function
    function sayHello():Void
    {
        proxy.call("sayHello", "Homer");
    }
    
    //This gets called when a value is returned from the sayHello function in
    //JavaScript
    function sayHelloReturn(result:String):Void
    {
        //dispatch event that javascript function has returned
        dispatchEvent({target:this, type:"onSayHelloReturn", result:result});
    }
}</code>


You can view another example [[projects:flashjs:tutorials:jsinfo2flash|here]].