ActionScript 3.0 Cookbook

Chapter 22. Building Integrated Applications

Introduction

The ExternalInterface class allows the Flash Player to communicate in a synchronous manner with the application within which it is embedded. In many cases that host application is a web browser. As such, this chapter focuses exclusively on how to build applications that integrate ActionScript and JavaScript when Flash Player is embedded in a browser.

Calling JavaScript Functions

Problem

You want to call a JavaScript function from ActionScript.

Solution

Use ExternalInterface.call().

Discussion

Use the ExternalInterface.call() method to make synchronous calls to JavaScript functions from ActionScript. The call() method requires at least one parameter as a string specifying the name of the function to call:

ExternalInterface.call("changeTitle");

The function must be defined in the HTML page with the same name:

<script language="JavaScript">
    function changeTitle(title) {
        if(title == undefined) {
            title = "New Title";
        }
        window.title = title;
    }
</script>

If the JavaScript function accepts parameters, you can pass values to it by adding additional parameters when calling the call() method. For example, the following passes a value to the changeTitle() function:

ExternalInterface.call("changeTitle", "ActionScript 3.0 Cookbook");

Since call() is synchronous, any values returned by the JavaScript function are immediately returned to ActionScript. That means you can assign the return value from a call to a variable. The following ActionScript illustrates ...