Dynamic HTML, or DHTML, is an umbrella term An umbrella term is a word that provides a superset or grouping of related concepts, also called a hypernym for a collection of technologies used together to create interactive and animated web sites A website [citation needed] is a collection of related web pages, images, videos or other digital assets that are addressed relative to a common Uniform Resource Locator (URL), often consisting of only the domain name, or the IP address, and the root path ('/') in an Internet Protocol-based network. A web site is hosted on at least one web server,[1] by using a combination of a static markup language A markup language is a modern system for annotating a text in a way that is syntactically distinguishable from that text. The idea and terminology evolved from the "marking up" of manuscripts, i.e. the revision instructions by editors, traditionally written with a blue pencil on authors' manuscripts. Examples are typesetting instructions (such as HTML HTML, which stands for HyperText Markup Language, is the predominant markup language for web pages. It is written in the form of HTML elements consisting of "tags" surrounded by angle brackets within the web page content), a client-side scripting Client-side scripting generally refers to the class of computer programs on the web that are executed client-side, by the user's web browser, instead of server-side . This type of computer programming is an important part of the Dynamic HTML (DHTML) concept, enabling web pages to be scripted; that is, to have different and changing content language (such as JavaScript JavaScript is an implementation of the ECMAScript language standard and is typically used to enable programmatic access to computational objects within a host environment. It can be characterized as a prototype-based object-oriented scripting language that is dynamic, weakly typed and has first-class functions. It is also considered a functional), a presentation definition language (such as CSS Cascading Style Sheets is a style sheet language used to describe the presentation semantics (that is, the look and formatting) of a document written in a markup language. Its most common application is to style web pages written in HTML and XHTML, but the language can also be applied to any kind of XML document, including SVG and XUL), and the Document Object Model The Document Object Model is a cross-platform and language-independent convention for representing and interacting with objects in HTML, XHTML and XML documents. Aspects of the DOM (such as its "Elements") may be addressed and manipulated within the syntax of the programming language in use. The public interface of a DOM are specified in.[2]
DHTML allows scripting languages to change variables In computer programming, a variable is a facility for storing data. The current value of the variable is the data actually stored in the variable. Depending on the programming language in question, the data stored in the variable can be intentionally altered during the program run, thus causing its value to change, or vary, hence the name. The in a web page's definition language, which in turn affects the look and function of otherwise "static" HTML page 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 A dynamic web page is a hypertext document rendered to a World Wide Web user presenting content that has been customized or actualized for each individual viewing or rendition or that continually updates information as the page is displayed to the user. It is difficult to be precise about "dynamic web page beginnings" or chronology, is a broader concept — 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 Server-side scripting is a web server technology in which a user's request is fulfilled by running a script directly on the web server to generate dynamic web pages. It is usually used to provide interactive web sites that interface to databases or other data stores. This is different from client-side scripting where scripts are run by the viewing (such as PHP PHP: Hypertext Preprocessor is a widely used, general-purpose scripting language that was originally designed for web development to produce dynamic web pages. For this purpose, PHP code is embedded into the HTML source document and interpreted by a web server with a PHP processor module, which generates the web page document. As a general-purpose, Perl Perl is a high-level, general-purpose, interpreted, dynamic programming language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular amongst programmers. Larry Wall continues to oversee, or ASP.NET ASP.NET is a web application framework developed and marketed by Microsoft to allow programmers to build dynamic web sites, web applications and web services. It was first released in January 2002 with version 1.0 of the .NET Framework, and is the successor to Microsoft's Active Server Pages technology. ASP.NET is built on the Common Language) where the web server generates content before sending it to the client.
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Uses
DHTML allows authors to add effects to their pages that are otherwise difficult to achieve. For example, DHTML allows the page author to:
- Animate text and images in their document, independently moving each element from any starting point to any ending point, following a predetermined path or one chosen by the user.
- Embed a ticker that automatically refreshes its content with the latest news, stock quotes, or other data.
- Use a form to capture user input, and then process and respond to that data without having to send data back to the server.
- Include rollover buttons or drop-down menus.
A less common use is to create browser-based action games. During the late 1990s and early 2000s, a number of games were created using DHTML[citation needed], but differences between browsers made this difficult: many techniques had to be implemented in code to enable the games to work on multiple platforms. Recently browsers have been converging towards the web standards Web standards is a general term for the formal standards and other technical specifications that define and describe aspects of the World Wide Web. In recent years, the term has been more frequently associated with the trend of endorsing a set of standardized best practices for building web sites, and a philosophy of web design and development, which has made the design of DHTML games more viable. Those games can be played on all major browsers and they can also be ported to Widgets for Mac OS X Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, Mac OS X has been included with all new Macintosh computer systems. It is the successor to Mac OS 9, the final release of the "classic" Mac OS, which had been Apple's primary operating system since 198 and Gadgets for Windows Vista Windows Vista is an operating system expressed in several variations developed by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs, and media center PCs. Prior to its announcement on July 22, 2005, Windows Vista was known by its codename "Longhorn." Development was completed on November 8,, which are based on DHTML code.
The term "DHTML" has fallen out of use in recent years, as DHTML scripts often tended to not work well between various web browsers. DHTML may now be referred to as unobtrusive JavaScript coding (DOM Scripting The term DOM scripting refers to programmatically accessing the Document Object Model . In common usage, DOM scripting implies JavaScript. DOM scripting has its roots in Dynamic HTML (DHTML), but is more structured. It is the third pillar in the web standards movement), in an effort to place an emphasis on agreed-upon best practices while allowing similar effects in an accessible, standards-compliant way Progressive enhancement is a strategy for web design that emphasizes accessibility, semantic HTML markup, and external stylesheet and scripting technologies. Progressive enhancement uses web technologies in a layered fashion that allows everyone to access the basic content and functionality of a web page, using any browser or Internet connection,.
Some disadvantages of DHTML are that it is difficult to develop and debug Debugging is a methodical process of finding and reducing the number of bugs, or defects, in a computer program or a piece of electronic hardware, thus making it behave as expected. Debugging tends to be harder when various subsystems are tightly coupled, as changes in one may cause bugs to emerge in another. Many entire books have been written due to varying degrees of support among web browsers of the technologies involved, and that the variety of screen sizes means the end look can only be fine-tuned on a limited number of browser and screen-size combinations. Development for relatively recent browsers, such as Internet Explorer 5.0+ Microsoft Internet Explorer 5 is a graphical web browser released in March 1999 by Microsoft, primarily for Microsoft Windows, but initially with versions available for Apple Macintosh, Sun Solaris, and HP-UX. (See also Internet Explorer for Mac or for Unix.), Mozilla Firefox Mozilla Firefox is a free and open source web browser descended from the Mozilla Application Suite and managed by Mozilla Corporation. As of July 2010[update], Firefox was the second most widely used browser, with 22.91% of worldwide usage share of web browsers, according to Net Applications. Other sources put Firefox's usage share between 20% and 2.0+, and Opera Opera is a web browser and Internet suite developed by Opera Software. The browser handles common Internet-related tasks such as displaying web sites, sending and receiving e-mail messages, managing contacts, chatting on IRC, downloading files via BitTorrent, and reading Web feeds. Opera is offered free of charge for personal computers and mobile 7.0+, is aided by a shared Document Object Model. Basic DHTML support was introduced with Internet Explorer 4.0 Microsoft Internet Explorer 4 is a graphical web browser released in September 1997 by Microsoft, primarily for Microsoft Windows, but also with versions available for Apple Mac OS, Solaris, and HP-UX and marketed as "The Web the Way You Want It", although there was a basic dynamic system with Netscape Navigator 4.0 Netscape Navigator and Netscape are the names for the proprietary web browser popular in the 1990s, the flagship product of the Netscape Communications Corporation and the dominant web browser in terms of usage share, although by 2002 its usage had almost disappeared. This was partly due to the increased usage of Microsoft's Internet Explorer web.
Structure of a web page
See also: DOM events DOM events allow event-driven programming languages like JavaScript, JScript, ECMAScript, VBScript and Java to register various event handlers/listeners on the element nodes inside a DOM tree, e.g. HTML, XHTML, XUL and SVG documentsTypically a web page using DHTML is set up the following way:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>DHTML example</title>
<script type="text/javascript">
function init() {
myObj = document.getElementById("navigation");
// .... more code
}
window.onload=init;
</script>
</head>
<body>
<div id="navigation"></div>
<pre>
Often the code is stored in an external file; this is done by linking the file that contains the JavaScript.
This is helpful when several pages use the same script:
</pre>
<script type="text/javascript" src="myjavascript.js"></script>
</body>
</html>
In the above code, the blue code represents the DOCUMENT TYPE declaration, which specifies which version of markup code is used to create the website. The red code shows browser detection Javascript, which enables web pages to adjust to browser application standards and requirements.
Example: Displaying an additional block of text
The following code illustrates an often-used function. An additional part of a web page will only be displayed if the user requests it. In e-learning E-learning comprises all forms of electronically supported learning and teaching, which are procedural in character and aim to effect the construction of knowledge with reference to individual experience, practice and knowledge of the learner. Information and communication systems, whether networked or not, serve as specific media to implement the, such a function might be used to display additional hints or an answer that the student initially should not see.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
<title>Test</title>
<style type="text/css">
h2 {background-color: lightblue; width: 100%}
a {font-size: larger; background-color: goldenrod}
a:hover {background-color: gold}
#example1 {display: none; margin: 3%; padding: 4%; background-color: limegreen}
</style>
<script type="text/javascript">
function changeDisplayState (id) {
d=document.getElementById("showhide");
e=document.getElementById(id);
if (e.style.display == 'none' || e.style.display == "") {
e.style.display = 'block';
d.innerHTML = 'Hide example..............';
} else {
e.style.display = 'none';
d.innerHTML = 'Show example';
}
}
</script>
</head>
<body>
<h2>How to use a DOM function</h2>
<div><a id="showhide" href="javascript:changeDisplayState('example1')">Show example</a></div>
<div id="example1">
This is the example.
(Additional information, which is only displayed on request)...
</div>
<div>The general text continues...</div>
</body>
</html>
References
- ^ http://www.w3schools.com/Dhtml/default.asp
- ^ http://books.google.co.in/books?id=AuO923YJTX4C&pg=PA22&dq=dhtml+scripting+languages&ei=mT2CSui-I42SkATfu6GXCg#v=onepage&q=dhtml%20scripting%20languages&f=false
External links
- QuirksMode, a comprehensive site with test examples and instructions on how to write DHTML code which runs on several browsers.
- Introductory DHTML Tutorial for those taking their first steps in DHTML.
- HTML & DHTML Reference on MSDN
Categories: HTML
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Q. why the dhtml called dynamic one and html called static one???
Asked by sujan - Sun Jan 13 13:05:36 2008 - - 2 Answers - 0 Comments
