Do you know that you can call Java-Applet-public-methods from JavaScript?
I don't really know how you can use it, but it works.
For example, you have applet:

import javax.swing.JApplet;
import javax.swing.JLabel;

public class TestApplet extends JApplet {
	JLabel lbl;
	public void setLabelText(String text) {
		lbl.setText(text);
	}
	public void init() {
		lbl = new JLabel("This is java-applet");
		this.getContentPane().add(lbl);
	}
	
}

If you want to change text in applet with javascript, you can use code:

<APPLET code="TestApplet.class" width=240 height=40 id="myapplet"></APPLET>
<FORM>
<INPUT TYPE="text" value="Enter text here" id="myTextField"> 
<INPUT type=button value="Insert to applet" onclick="CallAppletMethod()">
<SCRIPT>
function CallAppletMethod() {
	var myApplet = document.getElementById('myapplet'); 
	var myParam = document.getElementById('myTextField').value;
	myApplet.setLabelText(myParam); //just call java-method, it's easy :)
}
</SCRIPT>

Working sample: