ECMAscript for XML

The educational technology and digital learning wiki
Jump to navigation Jump to search

This article or section is currently under construction

In principle, someone is working on it and there should be a better version in a not so distant future.
If you want to modify this page, please discuss it with the person working on it (see the "history")

Draft

ECMAscript for XML (ak E4X) is an extension to ECMAscript.

It is available in

Using E4X is considerably simpler than using the DOM. Maybe some day we will be back to the elegance of languages like LISP instead of fighting against obscure C/Java syntax.....


Usage patterns

Creating an E4X XML object

(1) The easiest way is to create a new variable and just create the XML structure like this. In ECMAScript 4 (e.g. ActionScript 3) you should define the type of the variable.

var instructions:XML  = <stepbystep>
  <doctitle></doctitle>
  <steps>
    <title></title>
  </steps>
 </stepbystep>;

Don't forget the ";" at the end since this instruction extends over several lines.

(1b) In JavaScript 1.6 (ECMAScript 3) you can't define types and you simply use:

 var instructions  = <stepbystep> ....

This the same principle as creating an array or an object like this:

 var arr = [item1,item2,item3];
 var obj = {a:"item 1",b:"item 2",c:"item 3"}

(2) You also can create an XML E4X object from a string with the new XML() constructor.

var instruction_string = "<stepbystep>

 <doctitle></doctitle>
 <steps>
   <title></title>
 </steps>
</stepbystep>";

var instruction2:XML = new XML(instruction_string);

(3) Computing expressions

to do: {...}

XML lists

XML lists are the other important datastructure in E4X. Lists are needed for example to hold results of queries (like NodeLists in the DOM model).

Here is a little example of an XML list:

    <step>
      <title>step 1</title>
    </step>
    <step>
      <title>step 2</title>
    </step>
    <step>
      <title>step 3</title>
    </step>


Accessing elements and attributes

Again, there is a similarity between E4X objects, arrays, and traditional Object.

(1) Using the "." syntax

Let's take an example:

var steps:XML =
 <stepbystep>   
  <doctitle>Sample document</doctitle>
  <info>
    <para>See <a href="http://edutechwiki.unige.ch/en/ECMAscript_for_XML">ECMAscript for XML</a></para>
  </info>
  <steps>
    <title>List of steps</title>
    <step>
      <title>step 1</title>
    </step>
    <step>
      <title>step 2</title>
    </step>
    <step>
      <title>step 3</title>
      <para>That was easy !</para>
    </step>
  </steps>
 </stepbystep>;


A little example

  • Story (look at the source of this file)

Links

Overviews

Introductions and tutorials

JavaScript
  • Fremantle, Paul and Anthony Elder (1005). AJAX and scripting Web services with E4X, Part 1, IBM Works, HTML
  • E4X by Mark. Useful as short manual !
Flash/ActionScript/Flex
  • E4X (Adobe, Flex, Getting Started)
Php
Namespaces

Standard and Manuals