The ECMA-262 Spec has said at section 8.2.6.2, when method [[DefaultValue]] of Object called with no typeHint, it should behave as if the hint were Number.

But ECMA-357 changed the rule upon XML object at section 9.1.1.5 to do always as String.

Then, according to defination upon the operator '+' at the section 11.4.1 of ECMA-357(essentially, there is almost no defference between it and the section 11.6.1 of ECMA-262), there is a fact as following:

a = <price>8.1</price>;
print(a * 5); // -> this got 40.5
print(a + 1); // -> we got not 9.1 but 8.11

Yes, that's sure! The operator '+' doesn't consist with the operator '*' and any other arithmetical operators('/', '-', '%'). I think that maybe a little mistake.

So ecmax has redefined the '+' operation for XMLs: if one operand is XML and another operand is Number, and also if the XML object can be converted as Number(but not NaN), then addition operation upon the two Number is applied; otherwise, it behaves as ECMA-357.

1, New type: SDO extends XML

    x = <a id='1' val='a'/>;
    s = new SDO(x);
    y = s.copy(); // get a xml copy for current value.
    print(y.toXMLString()); // -> "<a id='1' val='a'/>"

2, SDO objects consist of context sections and change summary section

    2.1 Each modifying operation on SDO object is always recorded into its changeSummary section
    2.2 The changeSummary section is read-only and can't be directly modified.
    2.3 Initially, the changeSummary section is empty for SDO object
    2.4 SDO object has a 'restore()' method to undo all modifications and empty the changeSummary section

3, SDO object internally uses an XMLList to represent both the xml content and its change summary.

    3.1 SDO object's toXMLString() method shows the content of the internal XMLList
    3.2 the changeSummary with a namespace 'ecmax.sdo' is the last section of the internal XMLList.
    3.3 SDO.length() = its XMLList.length() - 1
    3.4 By declaring xmlns:x='ecmax.sdo', the following attributes in changeSummary section have given meaning:
       x:r='ref' -> reference to retrieve current value in content sections
       x:c='list' -> space-separated list of references, each refers to created element in content sections
       x:d='list' -> space-separated list of references, each refers to deleted element's copy in summary section
       x:u='list' -> space-separated list of references, each refers to updated element's copy in summary section
       <x:text/> -> special element to refer to and/or backup unstructured text
------------------------------------------------------------------------
For example:

x = <a id="1" value="a" lock='true'>
  text in a
  <b id='b1'>text in b</b>
  string in a
  <c:d xmlns:c='foo/core' width='100' height='200'>draw oval here</c:d>
</a>;
x = new SDO(x);

x.@id = 2;
delete x.@value;
x.@name='A';
x.b.* = 'new text in b';
x.b.@name='b';
x.b.@id='b2';
x.*[2] = 'new string in a';
x.*[3].@width = 200;

print(x.copy());
print(x.toXMLString());
------------------------------------------------------------------------
System.out - <a id="2" lock="true" name="A">
  text in a
  <b id='b2' name='b'>new text in b</b>
  new string in a
  <c:d xmlns:c='foo/core' width='200' height='200'>draw oval here</c:d>
</a>
System.out - <a id="2" lock="true" name="A">
  text in a
  <b id='b2' name='b'>new text in b</b>
  new string in a
  <c:d xmlns:c='foo/core' width='200' height='200'>draw oval here</c:d>
</a>
<x:changeSummary xmlns:x="ecmax.sdo" x:u='*[0]'>
  <a x:r="*[0]" x:c="@name" x:u="@id *[1] *[2] *[3]" x:d="@value" id="1" value="a">
    <x:text x:r='*[0].*[0]'/>
    <b x:r='*[0].*[1]' x:u='@id *' x:c='@name' id='b1'>text in b</b>
    <x:text x:r='*[0].*[2]'>string in a</x:text>
    <c:d x:r="*[0].*[3]" x:u="@width" xmlns:c='foo/core' width='100' />
  </a>
</x:changeSummary>

/**
 *
 * Copyright (c) 2006 Uniera.org. All Rights Reserved.
 *
 * Licensed under "Free for Non-commercial Use" License.
 *
 */

import java.io.*;

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.FontData;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.*;
import org.uniera.swlet.Swlet;

/**
 * A simple demo Swlet
 *
 * @version 1.0A
 */
public class Demo extends Swlet {
    public void init(Shell shell) {
        new Scd(shell, SWT.NORMAL, getClass().getName());
    }
}

/**
 * Scd means source code displayer.
 *
 * @version 1.0A
 */
class Scd extends Composite {

    private Text textArea = null;

    private Font font = null;

    public Scd(Composite parent, int style, String cn) {
        super(parent, style);
        initialize(cn);
    }

    public void dispose() {
        super.dispose();
        if (font != null && !font.isDisposed()) {
            font.dispose();
        }
    }

    private void initialize(String cn) {
        this.setLayout(new FillLayout(SWT.VERTICAL));
        textArea = new Text(this, SWT.MULTI | SWT.READ_ONLY | SWT.V_SCROLL
                | SWT.H_SCROLL);
        // textArea.setEditable(false);
        font = new Font(null, new FontData("Courier New", 10, SWT.NORMAL));
        textArea.setFont(font);
        LineNumberReader reader = null;
        try {
            reader = new LineNumberReader(new InputStreamReader(getClass()
                    .getResourceAsStream(cn.replace('.', '/') + ".java")));
            for (String line = reader.readLine(); line != null;) {
                textArea.append(line);
                textArea.append("\n");
                line = reader.readLine();
            }
        } catch (Exception e) {
            textArea.append("No source code found :( \n\tclass -> " + cn);
            e.printStackTrace();
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e) {
                }
            }
        }
    }
}
2, zip *.class and Demo.java into demo.jar
3, create demo.html and write following html code into it:

<HTML> <HEAD> <META http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <TITLE>Swlet Demo: System properties show</TITLE> </HEAD> <BODY><center><table border=1> <tr><td align=center><h2>Swlet Demo: source code show</h2></td></tr> <tr><td> <embed name="swlet" type="application/x-swt-applet" width="640" height="480"     codebase="swlet.xpi#version=1,0,0,3"     src="demo.jar" code="Demo.class"     pluginspage="http://r1.ripway.com/uniera/pub/swlet.html" /> </td></tr> </table></center> </BODY> </HTML>

4, Open demo.html with Mozilla Firefox(be sure that npswlet.zip has been unzipped into to folder ${Firefox}/plugins, See the directory tree here).

See the current javadoc for Swlet here.

Main features of the Swlet API are:
1, Full Browser Interface

• Navigate to specified url
• Show text onto browser's status bar
• Get the parameters passed in by html code.
• Get the urls of current page.

2, Script Communication supported

• Call external scripts using eval() method;
• Export methods or fields to be called by external scripts.

It seems that I've no spare time to make an XPI installer, so just uploaded a zip package of it here.
-------------------------------------
Steps for evaluating:
1, Download and unzip it into plugins folder as:
2, Make sure that jre/jdk 1.4.2+ already installed on your machine.
3, Open this page: http://h1.ripway.com/uniera/swlet/demo/eval.html
4, Confirm the security prompt, then see the Swlet demo:

• Cartesian product

1. new operator: [left|right|full] join


2. new filter: .[] vs. .()

---

Output:

• like - new operator
  

var a = '000001';
var b = '%1';
var c = 1871;

then:

a like b -> true
c like b -> true

• using BigDecimal in Floating-Point Arithmetic

e.g.

5.2/0.0000065 -> 800000 (not 800000.0000000001 when using double)

A new sub-project, ecmax, is started based on Mozilla Rhino 1.6R5 to achieve goals:

• 2 for ECMA-262

• 2 for ECMA-357