Call Applet.getMethod() with javascript throws error msg : TypeError: Applet.getMethod() is not a function

问题

I have an applet that use JMF libraries, called like this :

<object id="cameraViewer"
    classid="java:MyApplet.class"
    type="application/x-java-applet"
    archive="myapplet.jar" height="197" width="159"
    align="middle" codebase=".">
    <param name="code"
        value="MyApplet" />
    <param NAME="MAYSCRIPT" VALUE="true" />
    <param name="appletWidth" value="250" />
    <param name="appletHeight" value="200" />
    <param name="archive" value="myapplet.jar" />
    <param name="JAVA_CODEBASE" value="." />
    <font color="red">Applet error</font>
</object>

then I call a javascript function :

var cameraViewer = document.getElementById('cameraViewer');
var deviceList = new Array(cameraViewer.listDevices());

In the second line of javascript code, an error is thrown in javascript console (TypeError: cameraViewer.listDevices is not a function).

this problem is thrown only when I use Windows 7 with Firefox 8.0.1

Because this code works fine with :

Windows 7 and Chrome
Windows 7 and Firefox 20
Windows XP and Firefox 8.0.1

Have you any Idea about this problem !!?

回答1:

i think you are trying to call the function whilst it's still not loaded yet (browsers behave differentely on applet loading, some load it synchronously while other don't).

it would be safer for you to check if the function exists before trying to call it , in case it doesn't , tell the browser to wait a few milli seconds .

here's a mock code for you:

    var cameraViewer = document.getElementById('cameraViewer');

    if (typeof(cameraViewer.listDevices) != "undefined") { 
    // safe to use the function
    var deviceList = new Array(cameraViewer.listDevices());
}
else{
  setTimeout(function() {
    var deviceList = new Array(cameraViewer.listDevices());
  }, 1000);
}

来源：https://stackoverflow.com/questions/16298597/call-applet-getmethod-with-javascript-throws-error-msg-typeerror-applet-get

标签

javascript

firefox

windows-7

applet

jmf