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67-495: Dynamic HTML , or DHTML , is a term which was used by some browser vendors to describe the combination of HTML , style sheets and client-side scripts ( JavaScript , VBScript , or any other supported scripts) that enabled the creation of interactive and animated documents. The application of DHTML was introduced by Microsoft with the release of Internet Explorer 4 in 1997. DHTML (Dynamic HTML) allows scripting languages, such as JavaScript, to modify variables and elements in
134-510: A Document type declaration (informally, a "doctype"). In browsers, the doctype helps to define the rendering mode—particularly whether to use quirks mode . The original purpose of the doctype was to enable the parsing and validation of HTML documents by SGML tools based on the Document type definition (DTD). The DTD to which the DOCTYPE refers contains a machine-readable grammar specifying
201-420: A DOM structure from an XML or JSON data, using JavaScript methods to parse the data and create the nodes accordingly. 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
268-459: 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: Another method is to use a JavaScript library or framework such as jQuery , AngularJS , 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
335-407: A contractor at CERN , proposed and prototyped ENQUIRE , a system for CERN researchers to use and share documents. In 1989, Berners-Lee wrote a memo proposing an Internet -based hypertext system. Berners-Lee specified HTML and wrote the browser and server software in late 1990. That year, Berners-Lee and CERN data systems engineer Robert Cailliau collaborated on a joint request for funding, but
402-469: A document without adding or removing elements. This helps keep documents small and the scripts that manipulate the document fast. The object model provides programmatic access to styles. This means you can change inline styles on individual elements and change style rules using simple JavaScript programming. Inline styles are CSS style assignments that have been applied to an element using the style attribute. You can examine and set these styles by retrieving
469-451: A hierarchical structure using JavaScript or other programming languages, and it can be done using several methods depending on the use case and the developer's preference. Because the DOM supports navigation in any direction (e.g., parent and previous sibling) and allows for arbitrary modifications, implementations typically buffer the document. However, a DOM need not originate in a serialized document at all, but can be created in place with
536-532: 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". After
603-451: A pair is the start tag , and the second is the end tag (they are also called opening tags and closing tags ). Another important component is the HTML document type declaration , which triggers standards mode rendering. The following is an example of the classic "Hello, World!" program : The text between < html > and </ html > describes the web page, and
670-449: 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. Nodes can have event handlers (also known as event listeners) attached to them. Once an event is triggered, the event handlers get executed. The principal standardization of
737-425: A start tag) and do not use an end tag. Many tags, particularly the closing end tag for the very commonly used paragraph element < p > , are optional. An HTML browser or other agent can infer the closure for the end of an element from the context and the structural rules defined by the HTML standard. These rules are complex and not widely understood by most HTML authors. The general form of an HTML element
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#1732790894734804-596: A user can give input/s like: Comments: Comments can help in the understanding of the markup and do not display in the webpage. There are several types of markup elements used in HTML: Most of the attributes of an element are name–value pairs , separated by = and written within the start tag of an element after the element's name. The value may be enclosed in single or double quotes, although values consisting of certain characters can be left unquoted in HTML (but not XHTML). Leaving attribute values unquoted
871-653: A web page's structure, which in turn affect the look, behavior, and functionality of otherwise "static" HTML content after the page has been fully loaded and during the viewing process. Thus the dynamic characteristic of DHTML is the way it functions while a page is viewed, not in its ability to generate a unique page with each page load. By contrast, a dynamic web page is a broader concept, covering any web page generated differently for each user, load occurrence, or specific variable values. This includes pages created by client-side scripting and ones created by server-side scripting (such as PHP , Python , JSP or ASP.NET ) where
938-464: Is considered unsafe. In contrast with name-value pair attributes, there are some attributes that affect the element simply by their presence in the start tag of the element, like the ismap attribute for the img element. There are several common attributes that may appear in many elements : The abbreviation element, abbr , can be used to demonstrate some of these attributes: This example displays as HTML ; in most browsers, pointing
1005-456: Is for HTML5. If a declaration is not included, various browsers will revert to " quirks mode " for rendering. HTML documents imply a structure of nested HTML elements . These are indicated in the document by HTML tags , enclosed in angle brackets thus: < p > . In the simple, general case, the extent of an element is indicated by a pair of tags: a "start tag" < p > and "end tag" </ p > . The text content of
1072-455: Is rendered in browsers, the browser downloads the HTML into local memory and automatically parses it to display the page on screen. However, the DOM does not necessarily need to be represented as a tree, and some browsers have used other internal models. When a web page is loaded, the browser creates a Document Object Model of the page, which is an object oriented representation of an HTML document that acts as an interface between JavaScript and
1139-516: Is the product of three related and complementary technologies: HTML, Cascading Style Sheets (CSS), and JavaScript . To allow scripts and components to access features of HTML and CSS, the contents of the document are represented as objects in a programming model known as the Document Object Model (DOM). The DOM API is the foundation of DHTML, providing a structured interface that allows access and manipulation of virtually anything in
1206-401: Is therefore: < tag attribute1 = "value1" attribute2 = "value2" > ''content'' </ tag > . Some HTML elements are defined as empty elements and take the form < tag attribute1 = "value1" attribute2 = "value2" > . Empty elements may enclose no content, for instance, the < br /> tag or
1273-483: The Document Object Model (DOM) and page style. The combination of HTML, CSS, and JavaScript offers ways to: A less common use is to create browser-based action games. Although a number of games were created using DHTML during the late 1990s and early 2000s, differences between browsers made this difficult: many techniques had to be implemented in code to enable the games to work on multiple platforms. Browsers have since then converged toward web standards , which has made
1340-589: The Internet Engineering Task Force (IETF) with the mid-1993 publication of the first proposal for an HTML specification, the "Hypertext Markup Language (HTML)" Internet Draft by Berners-Lee and Dan Connolly , which included an SGML Document type definition to define the syntax. The draft expired after six months, but was notable for its acknowledgment of the NCSA Mosaic browser's custom tag for embedding in-line images, reflecting
1407-696: The WHATWG , which continues to maintain a living standard. In 2009, the Web Applications group reorganized DOM activities at the W3C. In 2013, due to a lack of progress and the impending release of HTML5 , the DOM Level 4 specification was reassigned to the HTML Working Group to expedite its completion. Meanwhile, in 2015, the Web Applications group was disbanded and DOM stewardship passed to
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#17327908947341474-434: The de facto web standard for some time. HTML markup consists of several key components, including those called tags (and their attributes ), character-based data types , character references and entity references . HTML tags most commonly come in pairs like < h1 > and </ h1 > , although some represent empty elements and so are unpaired, for example < img > . The first tag in such
1541-471: The web server generates content before sending it to the client. DHTML is the predecessor of Ajax and DHTML pages are still request/reload-based. Under the DHTML model, there may not be any interaction between the client and server after the page is loaded; all processing happens on the client side. By contrast, Ajax extends features of DHTML to allow the page to initiate network requests (or 'subrequest') to
1608-549: The " browser wars " of the late 1990s between Netscape Navigator and Microsoft Internet Explorer , as well as with that of JavaScript and JScript , the first scripting languages to be widely implemented in the JavaScript engines of web browsers . JavaScript was released by Netscape Communications in 1995 within Netscape Navigator 2.0. Netscape's competitor, Microsoft , released Internet Explorer 3.0
1675-457: The DOM API. And even before the idea of the DOM originated, there were implementations of equivalent structure with persistent disk representation and rapid access, for example DynaText 's model disclosed in and various database approaches. Web browsers rely on layout engines to parse HTML into a DOM. Some layout engines, such as Trident/MSHTML , are associated primarily or exclusively with
1742-417: The DOM tree as: 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 operations, such as getElementById , createElement , appendChild , and innerHTML . Another way to create
1809-423: The DOM tree. Text nodes do not have attributes or child nodes, and are always leaf nodes in the tree. For example, the text content "My Website" in the title element and "Welcome" in the h1 element in the above example are both represented as text nodes. Attributes of an element are represented as properties of the element node in the DOM tree. For example, an element with the following HTML: will be represented in
1876-608: 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: The history of the Document Object Model is intertwined with the history of
1943-451: The DTD in order to properly parse the document and to perform validation. In modern browsers, a valid doctype activates standards mode as opposed to quirks mode . Document Object Model The Document Object Model ( DOM ) is a cross-platform and language-independent interface that treats an HTML or XML document as a tree structure wherein each node is an object representing
2010-456: The IETF's philosophy of basing standards on successful prototypes. Similarly, Dave Raggett 's competing Internet Draft, "HTML+ (Hypertext Markup Format)", from late 1993, suggested standardizing already-implemented features like tables and fill-out forms. After the HTML and HTML+ drafts expired in early 1994, the IETF created an HTML Working Group. In 1995, this working group completed "HTML 2.0",
2077-529: The Web Platform group. Beginning with the publication of DOM Level 4 in 2015, the W3C creates new recommendations based on snapshots of the WHATWG standard. To render a document such as a HTML page, most web browsers use an internal model similar to the DOM. The nodes of every document are organized in a tree structure , called the DOM tree , with the topmost node named as "Document object". When an HTML page
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2144-494: The XML syntax for HTML and is no longer being developed as a separate standard. On 28 May 2019, the W3C announced that WHATWG would be the sole publisher of the HTML and DOM standards. The W3C and WHATWG had been publishing competing standards since 2012. While the W3C standard was identical to the WHATWG in 2007 the standards have since progressively diverged due to different design decisions. The WHATWG "Living Standard" had been
2211-473: The attribute value itself. If document authors overlook the need to escape such characters, some browsers can be very forgiving and try to use context to guess their intent. The result is still invalid markup, which makes the document less accessible to other browsers and to other user agents that may try to parse the document for search and indexing purposes for example. Escaping also allows for characters that are not easily typed, or that are not available in
2278-574: The browser, and these characteristics can be altered or enhanced by the web page designer's additional use of CSS . Many of the text elements are mentioned in the 1988 ISO technical report TR 9537 Techniques for using SGML , which describes the features of early text formatting languages such as that used by the RUNOFF command developed in the early 1960s for the CTSS (Compatible Time-Sharing System) operating system. These formatting commands were derived from
2345-486: The building blocks of HTML pages. With HTML constructs, images and other objects such as interactive forms may be embedded into the rendered page. HTML provides a means to create structured documents by denoting structural semantics for text such as headings, paragraphs, lists, links , quotes, and other items. HTML elements are delineated by tags , written using angle brackets . Tags such as < img > and < input > directly introduce content into
2412-433: The characters < and & (when written as < and & , respectively) to be interpreted as character data, rather than markup. For example, a literal < normally indicates the start of a tag, and & normally indicates the start of a character entity reference or numeric character reference; writing it as & or & or & allows & to be included in
2479-441: The characters of the world's writing systems. HTML defines several data types for element content, such as script data and stylesheet data, and a plethora of types for attribute values, including IDs, names, URIs , numbers, units of length, languages, media descriptors, colors, character encodings, dates and times, and so on. All of these data types are specializations of character data. HTML documents are required to start with
2546-451: The commands used by typesetters to manually format documents. However, the SGML concept of generalized markup is based on elements (nested annotated ranges with attributes) rather than merely print effects, with separate structure and markup. HTML has been progressively moved in this direction with CSS. Berners-Lee considered HTML to be an application of SGML. It was formally defined as such by
2613-458: The content and structure of web content . It is often assisted by technologies such as Cascading Style Sheets (CSS) and scripting languages such as JavaScript, a programming language. Web browsers receive HTML documents from a web server or from local storage and render the documents into multimedia web pages. HTML describes the structure of a web page semantically and originally included cues for its appearance. HTML elements are
2680-539: The content of an element or in the value of an attribute. The double-quote character ( " ), when not used to quote an attribute value, must also be escaped as " or " or " when it appears within the attribute value itself. Equivalently, the single-quote character ( ' ), when not used to quote an attribute value, must also be escaped as ' or ' (or as ' in HTML5 or XHTML documents ) when it appears within
2747-664: The cursor at the abbreviation should display the title text "Hypertext Markup Language." Most elements take the language-related attribute dir to specify text direction, such as with "rtl" for right-to-left text in, for example, Arabic , Persian or Hebrew . As of version 4.0, HTML defines a set of 252 character entity references and a set of 1,114,050 numeric character references , both of which allow individual characters to be written via simple markup, rather than literally. A literal character and its markup counterpart are considered equivalent and are rendered identically. The ability to " escape " characters in this way allows for
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2814-405: The day-to-day difficulties in cross-browser DOM manipulation, though better standards compliance among browsers has reduced the need for this. Typically a web page using DHTML is set up in the following way: The following code illustrates an often-used function. An additional part of a web page will only be displayed if the user requests it. DHTML is not a technology in and of itself; rather, it
2881-435: The design of DHTML games more viable. Those games can be played on all major browsers and in desktop and device applications that support embedded browser contexts. The term "DHTML" has fallen out of use in recent years as it was associated with practices and conventions that tended to not work well between various web browsers. DHTML support with extensive DOM access was introduced with Internet Explorer 4.0 . Although there
2948-421: The document itself. This allows the creation of dynamic web pages , because within a page JavaScript can: A Document Object Model (DOM) tree is a hierarchical representation of an HTML or XML document. It consists of a root node, which is the document itself, and a series of child nodes that represent the elements, attributes, and text content of the document. Each node in the tree has a parent node, except for
3015-589: The document's character encoding , to be represented within the element and attribute content. For example, the acute-accented e ( é ), a character typically found only on Western European and South American keyboards, can be written in any HTML document as the entity reference é or as the numeric references é or é , using characters that are available on all keyboards and are supported in all character encodings. Unicode character encodings such as UTF-8 are compatible with all modern browsers and allow direct access to almost all
3082-401: The document. The HTML elements in the document are available as a hierarchical tree of individual objects, making it possible to examine and modify an element and its attributes by reading and setting properties and by calling methods. The text between elements is also available through DOM properties and methods. The DOM also provides access to user actions such as pressing a key and clicking
3149-445: The element, if any, is placed between these tags. Tags may also enclose further tag markup between the start and end, including a mixture of tags and text. This indicates further (nested) elements, as children of the parent element. The start tag may also include the element's attributes within the tag. These indicate other information, such as identifiers for sections within the document, identifiers used to bind style information to
3216-439: The first HTML specification intended to be treated as a standard against which future implementations should be based. Further development under the auspices of the IETF was stalled by competing interests. Since 1996, the HTML specifications have been maintained, with input from commercial software vendors, by the World Wide Web Consortium (W3C). In 2000, HTML became an international standard ( ISO / IEC 15445:2000). HTML 4.01
3283-423: The following year with a reimplementation of JavaScript called JScript. JavaScript and JScript let web developers create web pages with client-side interactivity. The limited facilities for detecting user-generated events and modifying the HTML document in the first generation of these languages eventually became known as "DOM Level 0" or "Legacy DOM." No independent standard was developed for DOM Level 0, but it
3350-412: The head, for example: HTML headings are defined with the < h1 > to < h6 > tags with H1 being the highest (or most important) level and H6 the least: The effects are: CSS can substantially change the rendering. Paragraphs: < br /> . The difference between < br /> and < p > is that < br /> breaks a line without altering
3417-425: The hyperlink tag, these were strongly influenced by SGMLguid , an in-house Standard Generalized Markup Language (SGML)-based documentation format at CERN. Eleven of these elements still exist in HTML 4. HTML is a markup language that web browsers use to interpret and compose text, images, and other material into visible or audible web pages. Default characteristics for every item of HTML markup are defined in
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#17327908947343484-402: The inline < img > tag. The name of an HTML element is the name used in the tags. The end tag's name is preceded by a slash character, / , and that in empty elements the end tag is neither required nor allowed. If attributes are not mentioned, default values are used in each case. Header of the HTML document: < head > ... </ head > . The title is included in
3551-465: The look and layout of content. The World Wide Web Consortium (W3C), former maintainer of the HTML and current maintainer of the CSS standards, has encouraged the use of CSS over explicit presentational HTML since 1997. A form of HTML, known as HTML5 , is used to display video and audio, primarily using the < canvas > element, together with JavaScript. In 1980, physicist Tim Berners-Lee ,
3618-408: The mouse. It is possible to intercept and process these and other events by creating event handler functions and routines. The event handler receives control each time a given event occurs and can carry out any appropriate action, including using the DOM to change the document. Dynamic styles are a key feature of DHTML. By using CSS, one can quickly change the appearance and formatting of elements in
3685-413: The page. Other tags such as < p > and </ p > surround and provide information about document text and may include sub-element tags. Browsers do not display the HTML tags but use them to interpret the content of the page. HTML can embed programs written in a scripting language such as JavaScript , which affects the behavior and content of web pages. The inclusion of CSS defines
3752-434: The permitted and prohibited content for a document conforming to such a DTD. Browsers, on the other hand, do not implement HTML as an application of SGML and as consequence do not read the DTD. HTML5 does not define a DTD; therefore, in HTML5 the doctype declaration is simpler and shorter: An example of an HTML 4 doctype This declaration references the DTD for the "strict" version of HTML 4.01. SGML-based validators read
3819-412: The presentation of the document, and for some tags such as the < img > used to embed images, the reference to the image resource in the format like this: < img src = "example.com/example.jpg" > Some elements, such as the line break < br /> do not permit any embedded content, either text or further tags. These require only a single empty tag (akin to
3886-491: The project was not formally adopted by CERN. In his personal notes of 1990, Berners-Lee listed "some of the many areas in which hypertext is used"; an encyclopedia is the first entry. The first publicly available description of HTML was a document called "HTML Tags", first mentioned on the Internet by Tim Berners-Lee in late 1991. It describes 18 elements comprising the initial, relatively simple design of HTML. Except for
3953-408: The root node, and can have multiple child 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: will be represented in the DOM tree as: Text content within an element is represented as a text node in
4020-471: The semantic structure of the page, whereas < p > sections the page into paragraphs . The element < br /> is an empty element in that, although it may have attributes, it can take no content and it may not have an end tag. This is a link in HTML. To create a link the < a > tag is used. The href attribute holds the URL address of the link. There are many possible ways
4087-401: The server even after page load to perform additional actions. For example, if there are multiple tabs on a page, the pure DHTML approach would load the contents of all tabs and then dynamically display only the one that is active, while AJAX could load each tab only when it is really needed. DHTML allows authors to add effects to their pages that are otherwise difficult to achieve, by changing
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#17327908947344154-645: The standardization of ECMAScript , the W3C DOM Working Group began drafting a standard DOM specification. The completed specification, known as "DOM Level 1", became a W3C Recommendation in late 1998. By 2005, large parts of W3C DOM were well-supported by common ECMAScript-enabled browsers, including Internet Explorer 6 (from 2001), Opera , Safari and Gecko -based browsers (like Mozilla , Firefox , SeaMonkey and Camino ). The W3C DOM Working Group published its final recommendation and subsequently disbanded in 2004. Development efforts migrated to
4221-412: The style object for an individual element. For example, to highlight the text in a heading when the user moves the mouse pointer over it, you can use the style object to enlarge the font and change its color, as shown in the following simple example. HTML Hypertext Markup Language ( HTML ) is the standard markup language for documents designed to be displayed in a web browser . It defines
4288-517: The text between < body > and </ body > is the visible page content. The markup text < title > This is a title </ title > defines the browser page title shown on browser tabs and window titles and the tag < div > defines a division of the page used for easy styling. Between < head > and </ head > , a < meta > element can be used to define webpage metadata. The Document Type Declaration <!DOCTYPE html>
4355-498: Was a basic dynamic system with Netscape Navigator 4.0 , not all HTML elements were represented in the DOM. When DHTML-style techniques became widespread, varying degrees of support among web browsers for the technologies involved made them difficult to develop and debug . Development became easier when Internet Explorer 5.0+ , Mozilla Firefox 2.0+, and Opera 7.0+ adopted a shared DOM inherited from ECMAScript . Later, JavaScript libraries such as jQuery abstracted away many of
4422-794: Was partly described in the specifications for HTML 4 . Legacy DOM was limited in the kinds of elements that could be accessed. Form , link and image elements could be referenced with a hierarchical name that began with the root document object. A hierarchical name could make use of either the names or the sequential index of the traversed elements. For example, a form input element could be accessed as either document.myForm.myInput or document.forms[0].elements[0] . The Legacy DOM enabled client-side form validation and simple interface interactivity like creating tooltips . 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
4489-515: Was published in late 1999, with further errata published through 2001. In 2004, development began on HTML5 in the Web Hypertext Application Technology Working Group (WHATWG), which became a joint deliverable with the W3C in 2008, and was completed and standardized on 28 October 2014. XHTML is a separate language that began as a reformulation of HTML 4.01 using XML 1.0. It is now referred to as
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