bg_image
header

Dynamic HTML - DHTML

Dynamic HTML (DHTML) is a combination of technologies used to create interactive and dynamic web content. It’s not a standalone standard or programming language but rather a collection of techniques and tools that work together. DHTML enables websites to update content dynamically and provide interactivity without reloading the entire page.

Components of DHTML

  1. HTML (Hypertext Markup Language)
    Provides the basic structure of the webpage.

  2. CSS (Cascading Style Sheets)
    Controls the appearance and layout of the webpage. CSS can be dynamically altered to create effects like hover states or style changes.

  3. JavaScript
    Adds interactivity and dynamic behavior, such as updating content without a page reload.

  4. DOM (Document Object Model)
    A programming interface that allows access to and manipulation of the webpage’s structure. JavaScript interacts with the DOM to change content or add new elements.

What makes DHTML special?

  • Interactivity: Content and styles respond to user input.
  • Animations: Elements like text or images can move or animate.
  • Dynamic Content Updates: Parts of the webpage can change without reloading.
  • Improved User Experience: Offers real-time actions for users.

Example of DHTML

Here’s a simple example of a button changing text dynamically:

<!DOCTYPE html>
<html>
<head>
    <style>
        #text {
            color: blue;
            font-size: 20px;
        }
    </style>
    <script>
        function changeText() {
            document.getElementById("text").innerHTML = "Text changed!";
            document.getElementById("text").style.color = "red";
        }
    </script>
</head>
<body>
    <p id="text">Original text</p>
    <button onclick="changeText()">Click me</button>
</body>
</html>

Advantages of DHTML:

  • Increases interactivity and dynamism on a website.
  • Reduces server load as fewer page reloads are needed.
  • Allows for personalized user experiences.

Disadvantages:

  • May cause compatibility issues with older browsers or devices.
  • Requires more development effort and complex debugging.
  • Relies on JavaScript, which some users may disable.

Nowadays, DHTML has been largely replaced by modern techniques like AJAX and frameworks (e.g., React, Vue.js). However, it was a crucial step in the evolution of interactive web applications.

 

 


Document Object Model - DOM

The Document Object Model (DOM) is a standardized interface provided by web browsers to represent and programmatically manipulate structured documents, especially HTML and XML documents. It describes the hierarchical structure of a document as a tree, where each node represents an element, attribute, or text.

Key Features of the DOM:

  1. Tree Structure:

    • An HTML document is represented as a hierarchical tree. The root is the <html> element, with child nodes such as <head>, <body>, <div>, <p>, etc.
  2. Object-Oriented Representation:

    • Each element in the document is represented as an object that can be accessed and modified through methods and properties.
  3. Interactivity:

    • The DOM allows developers to modify content and styles of a webpage at runtime. For instance, JavaScript scripts can change the text of a <p> element or insert a new <div>.
  4. Platform and Language Agnostic:

    • Although commonly used with JavaScript, the DOM can also be manipulated using other languages like Python, Java, or PHP.

Examples of DOM Manipulation:

1. Accessing an Element:

let element = document.getElementById("myElement");

2. Changing Content:

element.textContent = "New Text";

3. Adding a New Element:

let newNode = document.createElement("div");
document.body.appendChild(newNode);

Important Note:

The DOM is defined and maintained by the W3C (World Wide Web Consortium) standards and is constantly updated to support modern web technologies.

 

 

 


Markdown

Markdown is a lightweight markup language designed to create easily readable and simultaneously formattable text. It is often used to format text in websites, documentation, and other text-based formats. Markdown files use the .md or .markdown file extension.

Here are some basic elements of Markdown:

  1. Headings:

    • # Heading 1
    • ## Heading 2
    • ### Heading 3
  2. Text Formatting:

    • Italic: *italic* or _italic_
    • Bold: **bold** or __bold__
    • Strikethrough: ~~strikethrough~~
  3. Lists:

    • Unordered list:
      • * Item 1
      • * Item 2
    • Ordered list:
      • 1. Item 1
      • 2. Item 2
  4. Links:

    • [Link text](URL)
  5. Images:

    • ![Alt text](Image URL)
  6. Code:

    • Inline code: `code`
  7. Blockquotes:

    • > This is a quote
  8. Horizontal Line:

    • --- or ***

Markdown is particularly useful because it is easily readable even when not rendered. This makes it ideal for use in versioning and collaboration systems like GitHub, where users can directly view and edit text files.

 

 


Extensible Hypertext Markup Language - XHTML

XHTML (Extensible Hypertext Markup Language) is a variant of HTML (Hypertext Markup Language) that is based on XML (Extensible Markup Language). XHTML combines the flexibility of HTML with the strictness and structure of XML. Here are some key aspects and features of XHTML:

  1. Structure and Syntax:

    • Well-formedness: XHTML documents must be well-formed, meaning they must adhere to all XML rules. This includes correctly nested and closed tags.
    • Elements and Attributes: All elements and attributes in XHTML must be written in lowercase.
    • Closing Tags: All tags must be closed, either with a corresponding end tag (e.g., <p></p>) or as self-closing tags (e.g., <img />).
  2. Compatibility:

    • XHTML is designed to be backward compatible with HTML. Many web browsers can render XHTML documents even if they were initially developed for HTML documents.
    • XHTML documents are treated as XML documents, meaning they can be parsed by XML parsers. This facilitates the integration of XHTML with other XML-based technologies.
  3. Doctype Declaration:

    • An XHTML document begins with a doctype declaration that specifies the document type and the version of XHTML being used. For example:
      <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
  4. Practical Use:

    • XHTML was developed to address the shortcomings of HTML and provide a stricter structure that improves document interoperability and processing.
    • Although XHTML offers many advantages, it has not been fully adopted. HTML5, the latest version of HTML, incorporates many of XHTML's benefits while maintaining the flexibility and ease of use of HTML.
  5. Different XHTML Profiles:

    • XHTML 1.0: The first version of XHTML, offering three different DTDs (Document Type Definitions): Strict, Transitional, and Frameset.
    • XHTML 1.1: An advanced version of XHTML that provides a more modular structure and better support for international applications.
    • XHTML Basic: A simplified version of XHTML specifically designed for mobile devices and other limited environments.

In summary, XHTML is a stricter and more structured variant of HTML based on XML, offering advantages in certain application areas. It was developed to improve web interoperability and standardization but has not been fully adopted due to the advent of HTML5.


RelaxNG

RelaxNG (Regular Language for XML Next Generation) is an alternative method for defining XML schemas. It is an XML-based language for describing the structure of XML documents and validating their conformity to that structure.

Compared to other XML schema languages like XML Schema Definition (XSD), RelaxNG is known for its simplicity and clarity. It provides various ways to define the structure of XML documents, including defining elements, attributes, data types, and relationships between elements. RelaxNG also supports advanced features such as pattern matching and substitution rules.

RelaxNG can be written in either a compact syntax or an XML syntax, providing flexibility in authoring and readability. It is an open specification and is supported by various XML processing tools and libraries.

Overall, RelaxNG offers an alternative way to structure and validate XML documents and is used by developers and organizations looking for a simpler and clearer alternative to other XML schema languages.

 


XML Schema Definition - XSD

XML Schema Definition (XSD) is a language-specific way of describing and validating structured data in XML documents. It is a technology used to formally define the structure and content of XML documents. XML schemas are used to ensure that XML data is formatted according to prescribed rules and structures.

An XML schema defines the elements, attributes, and data types that can be used in an XML document, as well as the possible relationships between these elements. It allows developers to precisely define the structure of an XML document, including the allowed elements, the order in which they can occur, their possible attributes, and the data types for element values.

By using XML schemas, developers can ensure that XML data is correctly structured and adheres to specified rules. This facilitates interoperability between different systems by ensuring that XML data is formatted according to established standards. XML schemas are commonly used in applications such as web services, databases, and other systems that utilize XML for data transmission and storage.

 


Document Type Definition - DTD

A Document Type Definition (DTD) is a specification-based method for describing the structure and content of XML documents. A DTD defines the rules and constraints for the elements and attributes that can be used in an XML document, as well as their arrangement and hierarchy.

Generally, a DTD defines:

  1. Elements: The names of elements that can be used in an XML document, along with their possible nesting and relationships to each other.
  2. Attributes: The attributes that can be associated with individual elements, along with their types and values.
  3. Entities: Entities are used to define reusable blocks of text, markup, or other elements within a document.
  4. Notations: Notations describe how non-XML content (such as images or multimedia data) can be embedded within an XML document.

There are two types of DTDs: internal DTDs and external DTDs. An internal DTD is defined within the XML document itself, while an external DTD is stored in a separate file and then referenced via a declaration in the XML document.

DTDs were the initial method for defining the structure of XML documents and are still commonly used today. However, XML schema languages such as XML Schema Definition (XSD) and RelaxNG have in many cases supplanted DTDs as the preferred method for structure definition, as they offer more powerful and flexible capabilities.

 


Extensible Markup Language - XML

XML stands for "eXtensible Markup Language" and is a widely used language for structuring and presenting data. Essentially, XML is used to organize information in a formatted, hierarchical manner. It's similar to HTML but much more flexible, allowing for the creation of custom tags to label specific types of data.

XML finds applications in various fields such as:

  1. Web Development: Used for data transmission between different systems or configuring web services.

  2. Databases: Facilitates data exchange between different applications or for storing structured data.

  3. Configuration Files: Many software applications use XML files to store settings or configurations.

  4. Document Exchange: Often used to exchange structured data between different platforms and applications.

XML uses tags similar to HTML to organize data. These tags are used in pairs (opening and closing tags) to denote the beginning and end of a particular data component. For example:

<Person>
  <Name>Max Mustermann</Name>
  <Age>30</Age>
  <Address>
    <Street>Main Street</Street>
    <City>Example City</City>
  </Address>
</Person>

Here, a simple XML structure is articlen containing information about a person including name, age, and address.

XML provides a flexible way to structure and store data, making it an essential tool in information processing and data exchange.


Hypertext Markup Language - HTML

HTML stands for "Hypertext Markup Language" and is a markup language used to structure content on the web. It serves as a foundation for web development, describing and organizing the content of a web page. HTML uses tags or markup to identify and structure different elements on a webpage.

A basic HTML document consists of HTML tags marking the beginning and end of elements. Here's an example of the basic structure of an HTML document:

<!DOCTYPE html>
<html>
<head>
    <title>Page Title</title>
</head>
<body>

    <h1>Heading 1</h1>
    <p>This is a paragraph.</p>
    
    <!-- More HTML elements here -->

</body>
</html>

Here are some basic HTML elements:

  • <html>: The root element that wraps around the entire HTML content.
  • <head>: Contains meta-information about the HTML document, such as the page title, references to CSS files, etc.
  • <title>: Defines the title of the webpage displayed in the browser tab.
  • <body>: Contains the actual content of the webpage, such as text, images, links, etc.
  • <h1>, <h2>, <h3>, ..., <h6>: Headings of different hierarchy levels.
  • <p>: A paragraph.
  • Comments are represented by <!-- comment -->.

HTML is often used in conjunction with CSS (Cascading Style Sheets) and JavaScript to not only structure content but also to style and provide interactivity to web pages.