Home > Articles > Design > Adobe Creative Suite

Flash Reference Guide

Aug 22, 2003

␡

⎙ Print

< Back Page 60 of 398 Next >

If you’re looking for more up-to-date information on this topic, please visit our Flash article, podcast, and store pages.

Over the last few years, Flash has used techniques such as FSCommands, FlashVars, and even a few LoadVars tricks to communicate to the Web browser through JavaScript. Despite these workarounds, communication between Flash and the Web page has never been easy. Enter the ExternalInterface class.

The ExternalInterface class, a brand new class within the Flash Player, allows you to more easily connect Flash with a Web page. The best part? ExternalInterface is not restricted to communicating with JavaScript. You can use it to communicate with VBScript in a Web page or even have the Flash movie communicate with programming languages such as C# if the Flash movie is placed within a Windows Form.

On the whole, however, most developers will use ExternalInterface to communicate Flash to a Web page and have the Web page communicate back via JavaScript. In fact, I'm betting it won't be long before the ExternalInterface class will become more commonly known as the JavaScript API.

You will be delighted to know that using the ExternalInterface class is quite straightforward. All you need is Flash, a Web page to which you can add some JavaScript, and a Web server to host your final pages. A word of caution at this point: the Flash Player has security that prevents the ExternalInterface Class from executing unless the Web page and SWF are running from a Web server.

There are three methods for the ExternalInterface Class that allow you to call an external interface (such as JavaScript), have the external interface call back (such as JavaScript being able to talk to Flash), and check whether or not you can communicate with JavaScript.

Checking Whether Flash Can Communicate

Let's start by checking to see whether or not you can communicate with JavaScript. This is useful in case the user has turned off JavaScript support in his Web browser.

The first step is to drag a Label component into the Library. This component will tell you whether or not JavaScript can be communicated to. Add the following JavaScript to the Layers panel:

import flash.external.*;
_root.attachMovie("Label", "lbl", 20);
lbl._x = 15;
lbl._y = 15;
lbl.text = "";
lbl.autoSize = "left";
var isAvailable:Boolean = ExternalInterface.available;
lbl.text = isAvailable;

The first line of the ActionScript allows Flash to import the ExternalInterface classes into the SWF. The next five lines of code are for the Label component. The final two lines call the ExternalInterface class to see if it is available. The "available" property has a true or false value. The results are then sent to the Label component.

You'll need to publish your files and move the SWF and HTML page to your Web server. From there you can view the page. It should look something like this:

I know this is not very exciting visually. But it gets better.

Communicating FROM Flash to a Web Page Through JavaScript

Now, let's make Flash talk to a Web page. You will need to add a TextInput and Button component to the Library. In Flash, add the following ActionScript to place the objects correctly on the Stage:

Now, you need to write a function in ActionScript that will use the ExternalInterface class to communicate with JavaScript:

sendButton.onRelease = function() {
  // Call Javascript function f
  ExternalInterface.call("f", txtOut.text);
}

Next, create an HTML page to which you can add some JavaScript. Create the basic page using this code:

<HTML>
 <HEAD>
 <meta http-equiv=Content-Type content="text/html; charset=ISO-8859-1">
 <TITLE>External Interface example</TITLE>
 </HEAD>
 <BODY>
 <OBJECT classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000"
     codebase="http://download.macromedia.com/pub/shockwave/
          cabs/flash/swflash.cab#version=5,0,0,0"
     WIDTH="400" HEIGHT="300" id="ExternalInterfaceExample">
  <param name="allowScriptAccess" value="always" />
  <param name="movie" value="ExternalInterfaceScript.swf" />
  <param name="quality" value="high" />
<param name="bgcolor" value="#ffffff" />
  <EMBED src="ExternalInterfaceScript.swf" quality=high
      bgcolor=#CCCCCC WIDTH="400" HEIGHT="300"
      NAME="ExternalInterfaceExample" swLiveConnect="true"
      ALLOWSCRIPTACCESS="always"
      TYPE="application/x-shockwave-flash"
      PLUGINSPAGE="http://www.macromedia.com/go/getflashplayer">
  </EMBED>
 </OBJECT>

 <h4>External Interface: Hello World - Javascript side</h4>
 <FORM NAME="inForm" METHOD="POST" ACTION="">
 Receiving from AS<BR>
 <INPUT TYPE="TEXT" NAME="inField" VALUE="No data received"><BR>
 </FORM>
 </BODY>
 </HTML>

You should have a simple page that has the Flash movie embedded to it through the OBJECT tag. Now, in the TITLE section of the page you need to add the following JavaScript:

<SCRIPT LANGUAGE=JavaScript>
  // This function "f" will be called from ActionScript
  function f(str)
  {
    document.inForm.inField.value = "AS says: Hello " + str;
  }
 </SCRIPT>

The "f" string binds the data between the two. Run the movie from your Web server and you'll be able to send a message from Flash to the Web page via JavaScript.

Communicating TO Flash From the Web Page Via JavaScript

Now, you're going to reverse the process. Add the following additional objects to your Flash movie:

_root.attachMovie("Label", "lblJs", 50);
lblJs._x = 15;
lblJs._y = 120;
lblJs._width = 150;
lblJs.autoSize = "left";
lblJs.text = "Receiving from Web page";

_root.attachMovie("TextInput", "txtIn", 60);
txtIn._x = 15;
txtIn._y = 150;
txtIn._width = 150;
txtIn.editable = false;

You'll also have to use a function in Flash to receive a request sent to it from the Web page. This is the function you can use:

function g(str:String) {
  txtIn.text = "JS says: Hello " + str;
}

// Make function g available to Javascript
ExternalInterface.addCallback("g", this, g);

To allow JavaScript to communicate back to Flash you need to add some additional HTML objects to the HTML code above. The code is:

<FORM NAME="outForm" METHOD="POST" ACTION="javascript:makeCall(document.outForm.outField.value)">
 Sending to AS<BR>
 <INPUT TYPE="TEXT" NAME="outField" VALUE="Enter your name"><BR>
<INPUT TYPE="SUBMIT" VALUE="Send to AS">
 </FORM>

The FORM action calls JavaScript. You need to add the following JavaScript to complete the communication:

  function makeCall(str)
  {
     thisMovie("ExternalInterfaceExample").g(str);
  }

Now, you can test your movie and Web page. You should be able to chat back and forth very easily. What you have worked through in these examples is only a taste of what you can do with the ExternalInterface class.

Why Communicate With JavaScript?

A number of years ago, Macromedia tried to convince the world that Flash would replace HTML. The reality, however, is that there are simply too few Flash ActionScript developers to displace the massive number of Web developers and tools. Today's reality is that Flash is merely a part of the overall Web site experience.

Web pages do a lot of things and Flash does a lot of things. Coupling the two gives you the best of both worlds. This is where the ExternalInterface class comes into play. Consider, for instance, if you were to create an AJAX Web application (AJAX is Asynchronous JavaScript and XML). Why not mix Flash and JavaScript together? By leveraging Flash's ExternalInterface class you can have the two technologies easily communicate with each other. Google's Earth project is a great example of this.

Today, the Google Earth project is one of the best examples of an AJAX application. Google, however, has had problems rendering the graphics in its Google Earth AJAX application. To resolve this issue, Google created a version of Google Earth specifically tailored for different Web browsers. This is where Flash using the ExternalInterface class can help. Instead of having multiple code bases, why not use Flash with ExternalInterface to handle the graphics for all browsers?

With your Flash movie tightly coupled to the Web application, you don't have to think of building either Flash or multiple AJAX sites. What you need to think about is how you can build hybrid Flash/AJAX sites. Maybe we could call this new technology F-JAX (Flash-JavaScript and XML)? You heard it here first, folks.

< Back Page 60 of 398 Next >

🔖 Save To Your Account

Peachpit Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from Peachpit and its family of brands. I can unsubscribe at any time.

Privacy Notice

Overview

Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about Peachpit products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites; develop new products and services; conduct educational research; and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email ask@peachpit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security

Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children

This site is not directed to children under the age of 13.

Marketing

Pearson may send or direct marketing communications to users, provided that

Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
Such marketing is consistent with applicable law and Pearson's legal obligations.
Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out

Users can always make an informed choice as to whether they should proceed with certain services offered by Adobe Press. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.peachpit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

As required by law.
With the consent of the individual (or their parent, if the individual is a minor)
In response to a subpoena, court order or legal process, to the extent permitted or required by law
To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
To investigate or address actual or suspected fraud or other illegal activities
To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links

This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020

Email Address