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How to Create a DOM tree

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-The [http://www.w3.org/TR/2004/REC-DOM-Level-3-Core-20040407/core.html W3C DOM API], supported by Mozilla, can be used to create an in-memory representation of this document like so:+The W3C DOM API, supported by Mozilla, can be used to create an in-memory representation of this document like so:
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==Alternatives== ==Alternatives==
-If you're writing JavaScript that is used in both XUL applications and HTML pages, and the HTML pages may be viewed in non-Gecko-based applications (such as Internet Explorer, Opera, Konqueror, Safari), you should consider using [https://sourceforge.net/projects/sarissa/ Sarissa]&mdash;a JavaScript wrapper for XML manipulation&mdash;to create DOM objects. <b>Note: Do not create a DOM object using <code>document.implementation.createDocument()</code> and then use [https://sourceforge.net/projects/sarissa/ Sarissa] classes and methods to manipulate that object.</b> It will not work. You must use [https://sourceforge.net/projects/sarissa/ Sarissa] to create the initial DOM object.+If you're writing JavaScript that is used in both XUL applications and HTML pages, and the HTML pages may be viewed in non-Gecko-based applications (such as Internet Explorer, Opera, Konqueror, Safari), you should consider using [https://sourceforge.net/projects/sarissa/ Sarissa]&mdash;a JavaScript wrapper for XML manipulation&mdash;to create DOM objects.
-==Resources==+''Note:'' Do not create a DOM object using <code>document.implementation.createDocument()</code> and then use Sarissa classes and methods to manipulate that object. It will not work. You must use Sarissa to create the initial DOM object.
-* [https://sourceforge.net/projects/sarissa/ Sarissa] - Sarissa is a cross-browser ECMAScript library for client side XML manipulation, including loading XML from URLs or strings, performing XSLT transformations, XPath queries and more. Supported: Gecko (Mozilla, Firefox etc), IE, KHTML (Konqueror, Safari).+
[[Category:Example code]] [[Category:XML in JavaScript]] [[Category:Example code]] [[Category:XML in JavaScript]]

Revision as of 19:55, 28 March 2005

This page is part of the extension development documentation project.

Ask your questions in MozillaZine Forums. Also try browsing example code.

Note: development documentation is in process of being moved to Mozilla Development Center (MDC).

This page describes how to use the DOM Core API in JavaScript to create and modify DOM objects. It applies to all Gecko-based applications (such as Firefox) both in priviledged (extensions) and unpriviledged (web pages) code.

Dynamically creating a DOM tree

Consider the following XML document:

<?xml version="1.0"?>
<people>
  <person first-name="eric" middle-initial="H" last-name="jung">
    <address street="321 south st" city="denver" state="co" country="usa"/>
    <address street="123 main st" city="arlington" state="ma" country="usa"/>
  </person>

  <person first-name="jed" last-name="brown">
    <address street="321 north st" city="atlanta" state="ga" country="usa"/>
    <address street="123 west st" city="seattle" state="wa" country="usa"/>
    <address street="321 south avenue" city="denver" state="co" country="usa"/>
  </person>
</people>

The W3C DOM API, supported by Mozilla, can be used to create an in-memory representation of this document like so:

var doc = document.implementation.createDocument("", "", null);
var peopleElem = doc.createElement("people");

var personElem1 = doc.createElement("person");
personElem1.setAttribute("first-name", "eric");
personElem1.setAttribute("middle-initial", "h");
personElem1.setAttribute("last-name", "jung");

var addressElem1 = doc.createElement("address");
addressElem1.setAttribute("street", "321 south st");
addressElem1.setAttribute("city", "denver");
addressElem1.setAttribute("state", "co");
addressElem1.setAttribute("country", "usa");
personElem1.appendChild(addressElem1);

var addressElem2 = doc.createElement("address");
addressElem2.setAttribute("street", "123 main st");
addressElem2.setAttribute("city", "arlington");
addressElem2.setAttribute("state", "ma");
addressElem2.setAttribute("country", "usa");
personElem1.appendChild(addressElem2);

var personElem2 = doc.createElement("person");
personElem2.setAttribute("first-name", "jed");
personElem2.setAttribute("last-name", "brown");

var addressElem3 = doc.createElement("address");
addressElem3.setAttribute("street", "321 north st");
addressElem3.setAttribute("city", "atlanta");
addressElem3.setAttribute("state", "ga");
addressElem3.setAttribute("country", "usa");
personElem2.appendChild(addressElem3);

var addressElem4 = doc.createElement("address");
addressElem4.setAttribute("street", "123 west st");
addressElem4.setAttribute("city", "seattle");
addressElem4.setAttribute("state", "wa");
addressElem4.setAttribute("country", "usa");
personElem2.appendChild(addressElem4);

var addressElem5 = doc.createElement("address");
addressElem5.setAttribute("street", "321 south avenue");
addressElem5.setAttribute("city", "denver");
addressElem5.setAttribute("state", "co");
addressElem5.setAttribute("country", "usa");
personElem2.appendChild(addressElem5);

peopleElem.appendChild(personElem1);
peopleElem.appendChild(personElem2);
doc.appendChild(peopleElem);

See also DOM chapter of XulPlanet's tutorial.

So What?

DOM trees can be queried using XPath expressions, converted to strings or written to a local or remote files using XMLSerializer (without having to first convert to a string), POSTed to a web server, transformed using XSLT, XLink'd to, etc.

You can use DOM trees to model data which isn't well-suited for RDF (or perhaps you just don't like RDF). Another application is that, since XUL is XML, the UI of your application can be dynamically manipulated, downloaded, uploaded, saved, loaded, converted, or transformed quite easily.

Alternatives

If you're writing JavaScript that is used in both XUL applications and HTML pages, and the HTML pages may be viewed in non-Gecko-based applications (such as Internet Explorer, Opera, Konqueror, Safari), you should consider using Sarissa—a JavaScript wrapper for XML manipulation—to create DOM objects.

Note: Do not create a DOM object using document.implementation.createDocument() and then use Sarissa classes and methods to manipulate that object. It will not work. You must use Sarissa to create the initial DOM object.