title: Flex/Flash 4 ExternalInterface.call - trying to get a string from HTML to Actionscript
body: <p>I need to obtain a string from HTML and put it into Actionscript.</p>
  
  <p>the actionscript:</p>
  
  <pre><code>import flash.external.ExternalInterface;
  protected function getUserName():void{
              var isAvailable:Boolean = ExternalInterface.available;
              var findUserName:String = "findUserName";
              if(isAvailable){
                  var foundUserName:String = ExternalInterface.call(findUserName).toString();
                  Alert.show(foundUserName);}}
  </code></pre>
  
  <p>the javascript:</p>
  
  <pre><code>function findUserName() {
      var label = document.getElementById("username-label");
      if(label.value != ""){
          alert("the name in the box is: " + label.value);
          return label.value;}
      else
          return "nothing in the textbox";}}
  </code></pre>
  
  <p>the JSP:</p>
  
  <pre><code>&lt;%IUserSession userSession = SessionManager.getSession();%&gt;
  
  &lt;logic:notEmpty name="userSession"&gt;
      &lt;logic:notEqual value="anonymous" name="userSession" property="userLoginId"&gt;
          &lt;td align="right" width="10%" &gt;
              &lt;input id="username-label" type="text" value="&lt;bean:write name="userSession" property="userLoginId"/&gt;" /&gt;
          &lt;/td&gt;
      &lt;/logic:notEqual&gt;
  &lt;/logic:notEmpty&gt;
  </code></pre>
  
  <p>the rendered HTML:</p>
  
  <pre><code>&lt;td align="right" width="10%"&gt;
      &lt;input id="username-label" type="text" value="a-valid-username" /&gt;
  &lt;/td&gt;
  </code></pre>
  
  <p>when the javascript execution hits</p>
  
  <pre><code>var label = document.getElementById("username-label");
  </code></pre>
  
  <p>a null is returned and crashes, no alert shows no error message is shown.
  I can successfully do a search firefox DOM Inspector by "username-label" (document.getElementById())</p>
  
  <p>The only alert box that pops up is the action script alert box and the contents are blank.</p>
  
  <p>firfox 3.5 windows, container is Tomcat.</p>
  
  <p>Please advise, and thank you in advance.</p>