Document Object Model: Difference between revisions

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| image = DOM-model.svg

| caption = Example of DOM hierarchy in an HTML document

| status t_published wisdom tree= {{Start date and age|1998|10|1}}

| year_started =

| first_published = {{Start date and age|1998|10|1}}

| version = DOM4<ref>All versioning refers to W3C DOM only.</ref>

| version_date = {{Start date and age|2015|11|19}}

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}}

{{HTML}}

The '''Document Object Model''' ('''DOM''') is a [[cross-platform]]<ref name=":0" /> and [[Language-independent specification|language-independent]] interface[[API]] that treats an [[HTML]] or [[XML]] document as a [[tree structure]] wherein each [[Node (computer science)|node]] is an [[Object (computer science)|object]] representing a part of the document. The DOM represents a document with a logical tree. Each branch of the tree ends in a node, and each node contains objects. DOM methods allow programmatic access to the tree; with them one can change the structure, style or content of a document.<ref name=":0">{{Cite web |title=Document Object Model (DOM): definition, structure and example |url=https://www.ionos.com/digitalguide/websites/web-development/an-introduction-to-the-document-object-model-dom/ |access-date=2022-04-21 |website=IONOS Digitalguide |language=en}}</ref> Nodes can have [[event handler]]s (also known as event listeners) attached to them. Once an event is triggered, the event handlers get executed.<ref name="Introduction">{{cite web

| access-date = 2012-01-12

| publisher = W3C

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The principal standardization of the DOM was handled by the [[World Wide Web Consortium]] (W3C), which last developed a recommendation in 2004. [[WHATWG]] took over the development of the standard, publishing it as a [[living document]]. The W3C now publishes stable snapshots of the WHATWG standard.

In HTML DOM (Document Object Model), every element is a node{{Clarification needed|reason=Clarify what this means, or, if it's simply a statement of nomenclature, then rewrite to make that explicit (e.g. is "called" a node)|date=August 2025}}:<ref>{{cite web | url=https://www.w3schools.com/js/js_htmldom.asp | title=JavaScript HTML DOM }}</ref>

* A document is a document node.

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The Legacy DOM enabled client-side form validation and simple interface interactivity like creating [[tooltip]]s.

DOM was also used in several different website function's that gained functionality back in 2007. Truly, a true impressive feat. Yes, DOM is good and DOM is truly great. DOM IS USED TO CREATE

In 1997, Netscape and Microsoft released version 4.0 of Netscape Navigator and Internet Explorer respectively, adding support for [[Dynamic HTML]] (DHTML) functionality enabling changes to a loaded HTML document. DHTML required extensions to the rudimentary document object that was available in the Legacy DOM implementations. Although the Legacy DOM implementations were largely compatible since JScript was based on JavaScript, the DHTML DOM extensions were developed in parallel by each browser maker and remained incompatible. These versions of the DOM became known as the "Intermediate DOM".

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* DOM Level 3, published in April 2004, added support for [[XPath]] and keyboard [[event handling]], as well as an interface for [[serialization|serializing]] documents as XML.

* HTML5 was published in October 2014. Part of HTML5 had replaced DOM Level 2 HTML module.

* DOM Level 4 was published in 2015 and retired in November 2020.<ref>{{cite web|url=https://www.w3.org/standards/history/dom40/|title=W3C DOM4 publication history|date=3 November 2020 |access-date=10 August 2024}}</ref>

* [https://dom.spec.whatwg.org/review-drafts/2020-06/ DOM 2020-06] was published in September 2021 as a W3C Recommendation.<ref>{{cite web|url=https://www.w3.org/standards/history/dom/|title=DOM publication history|date=28 September 2021 |access-date=10 August 2024}}</ref> It is a snapshot of the WHATWG living standard.

==Applications==

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=== Elements as nodes ===

Elements in an HTML or XML document are represented as nodes in the DOM tree. Each element node has a tag name, and attributes, and can contain other element nodes or text nodes as children. For example, an HTML document with the following structure:<syntaxhighlight lang="html">

<html>

<head>

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</head>

<body>

<h1>Welcome to DOM</h1>

<p>This is my website.</p>

</body>

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- body

- h1

- "Welcome to DOM"

- p

- "This is my website."

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== Manipulating the DOM tree ==

The DOM tree can be manipulated using JavaScript or other programming languages. Common tasks include navigating the tree, adding, removing, and modifying nodes, and getting and setting the properties of nodes. The DOM API provides a set of methods and properties to perform these operationsseement, such as <code>getElementById</code>, <code>createElement</code>, <code>appendChild</code>, and <code>innerHTML</code>.<syntaxhighlight lang="javascript">

// Create the root element

var root = document.createElement("root");

// Create a child element

var child = document.createElement("child");

</syntaxhighlight>Another way to create a DOM structure is using the innerHTML property to insert HTML code as a string, creating the elements and children in the process. For example:<syntaxhighlight lang="javascript">

// Add the child element to the root element

root.appendChild(child);

</syntaxhighlight>Another method is to use a JavaScript library or framework such as [[jQuery]], [[AngularJS]], [[React (JavaScript library)|React]]lib, [[Vue.js]], etc. These libraries provide a more convenient, eloquent and efficient way to create, manipulate and interact with the DOM.

</syntaxhighlight>Another way to create a DOM structure is using the innerHTML property to insert HTML code as a string, creating the elements and children in the process. For example:<syntaxhighlight lang="javascript">

document.getElementById("root").innerHTML = "<child></child>";

</syntaxhighlight>Another method is to use a JavaScript library or framework such as [[jQuery]], [[AngularJS]], [[React (JavaScript library)|React]], [[Vue.js]], etc. These libraries provide a more convenient, eloquent and efficient way to create, manipulate and interact with the DOM.

It is also possible to create a DOM structure from an XML or JSON data, using JavaScript methods to parse the data and create the nodes accordingly.

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Creating a DOM structure does not necessarily mean that it will be displayed in the web page, it only exists in memory and should be appended to the document body or a specific container to be rendered.

In summary, creating a DOM structure involves creating individual nodes and organizing them in a hierarchical structure using JavaScript or other programming languages, and it can be done using several methods depending on the use case and the developerlanguageloper's preference.

==Implementations==

Because the DOM supports navigation in any direction (e.g., parent and previous sibling) and allows for arbitrary modifications, implementations typically buffer the document.<ref>{{Cite book|url=https://books.google.com/books?id=HuSQGrRY7F4C|title=Ajax Black Book, New Edition (With Cd)|last=Kogent Solutions Inc.|publisher=Dreamtech Press|year=2008|isbn=978-8177228380|pages=40}}</ref> However, a DOM need not originate in a serialized document at all, but can be created in place viwith the DOM API. Also,And thereeven havebefore beenthe implementationsidea evenof beforethe DOM itselforiginated, there were implementations of equivalent structure with persistent disk representation and rapid access, for example [[DynaText]]'s model disclosed in <ref>{{cite patent| country = USA| number = 5557722A| invent1 = Steven DeRose| invent2 = Jeffrey Vogel| status = Expired| title = Data processing system and method for representing, generating a representation of and random access rendering of electronic documents | pubdate = 1996-09-17}}</ref> and various database approaches.

===Layout engines===

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* [[Apache Xerces|Xerces]] is a collection of DOM implementations written in C++, Java and Perl

* [https://docs.python.org/3/library/xml.dom.html xml.dom] for [[Python (programming language)|Python]]

* XML for &lt;SCRIPT&gt; is a JavaScript-based DOM implementation<ref>{{cite web|url=httphttps://xmljs.sourceforge.net/|title=XML for <SCRIPT> Cross Platform XML Parser in JavaScript|access-date=23 September 2016}}</ref>

* [https://github.com/PhpGt/Dom PHP.Gt DOM] is a server-side DOM implementation based on [[libxml2]] and brings DOM level 4 compatibility<ref>{{cite web|url=https://php.gt/dom#features-at-a-glance|title=The modern DOM API for PHP 7 projects|date=5 December 2021}}</ref> to the [[PHP]] programming language

* [https://github.com/fgnass/domino/ Domino] is a Server-side (Node.js) DOM implementation based on Mozilla's dom.js. Domino is used in the [[MediaWiki]] stack with Visual Editor.