DHTML Tutorial • •

DHTML is NOT a language. It is a TERM describing the art of making dynamic and interactive web pages. DHTML combines HTML, JavaScript, DOM, and CSS.

DHTML Introduction DHTML is the art of combining HTML, JavaScript, DOM, and CSS. What you should already know Before you continue you should have a basic understanding of the following: • HTML • JavaScript • CSS DHTML is NOT a Language • DHTML stands for Dynamic HTML.

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DHTML is NOT a language or a web standard. DHTML is a TERM used to describe the technologies used to make web pages dynamic and interactive. To most people DHTML means the combination of HTML, JavaScript, DOM, and CSS. According to the World Wide Web Consortium (W3C): "Dynamic HTML is a term used by some vendors to describe the combination of HTML, style sheets and scripts that allows documents to be animated."

DHTML Technologies Below is a listing of DHTML technologies. HTML 4 • The W3C HTML 4 standard has rich support for dynamic content: • HTML supports JavaScript • HTML supports the Document Object Model (DOM) • HTML supports HTML Events • HTML supports Cascading Style Sheets (CSS) • DHTML is about using these features to create dynamic and interactive web pages. JavaScript JavaScript is the scripting standard for HTML. DHTML is about using JavaScript to control, access and manipulate HTML elements. HTML DOM • The HTML DOM is the W3C standard Document Object Model for HTML.

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The HTML DOM defines a standard set of objects for HTML, and a standard way to access and manipulate them. DHTML is about using the DOM to access and manipulate HTML elements.

HTML Events

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The W3C HTML Event Model is a part of the HTML DOM. • It defines a standard way to handle HTML events. • DHTML is about creating web pages that reacts to (user)events. CSS CSS is the W3C standard style and layout model for HTML. CSS allows web developers to control the style and layout of web pages. HTML 4 allows dynamic changes to CSS. DHTML is about using JavaScript and DOM to change the style and positioning of HTML elements.

DHTML - JavaScript JavaScript can create dynamic HTML content.

Date: Mon Jun 01 2009 13:11:38 GMT+0800

JavaScript Alone If you have studied JavaScript, you know that the statement: document.write() is used to write output to a web page. Example Using JavaScript to display the current date: Example <script type="text/javascript"> document.write(Date());

JavaScript and the HTML DOM A JavaScript can also be used to change the content and attributes of HTML elements dynamically. To change the content of an HTML element: document.getElementById(id).innerHTML=new HTML To change the attribute of an HTML element: document.getElementById(id).attribute=new value You will learn more about JavaScript and the HTML DOM in the next chapter of this tutorial.

JavaScript and HTML Events A JavaScript can also be executed when an event occurs, like when a user clicks on an HTML element. To execute code when a user clicks on an element, use the following event attribute: onclick=JavaScript You will learn more about JavaScript and HTML Events in a later chapter.

JavaScript and CSS JavaScript can also change the style of HTML elements. To change the style of an HTML element: document.getElementById(id).style.property=new style

DHTML - HTML DOM What is the HTML DOM? • The HTML DOM is: • A Document Object Model for HTML • A standard programming interface for HTML • Platform- and language-independent • A W3C standard • The HTML DOM defines the objects and properties of all HTML elements, and the methods (interface) to access them. In other words: The HTML DOM is a standard for how to get, change, add, or delete HTML elements. Change an HTML Element The following example changes the content of an HTML h1 element: Example

Old Header

<script type="text/javascript"> document.getElementById("header").innerHTML="New Header";

Example explained: 1. The HTML document contains a header with id="header" 2. The DOM is used to get the element with id="header" 3. A JavaScript is used to change the HTML content (innerHTML) Change an HTML Attribute The following example changes the src attibute of an HTML img element: Example <script type="text/javascript"> document.getElementById("image").src="landscape.jpg"; Example explained: 1. The HTML document loads with an image with id="image" 2. The DOM is used to get the element with id="image" 3. A JavaScript changes the src attribute from smiley.gif to landscape.jpg

DHTML Event Handlers HTML events can trigger actions in the browser. Event handlers An event handler allows you to execute code when an event occurs. Events are generated by the browser when the user clicks an element, when the page loads, when a form is submitted, etc. In the following example, the h1 heading changes when a user clicks on it: Example

Click on this text

You can also add a script in the head section of the page and then call the function from the event handler: Example <script type="text/javascript"> function changetext(id) { id.innerHTML="Ooops!"; }

Click on this text

DHTML - CSS JavaScript and the HTML DOM can be used to change the style of any HTML element. Change Style of Current HTML Element

To change the style of the current HTML element, use the statement: this.style.property=new styleExample

Click Me!

Change Style of a Specific HTML Element To change the style of a specific HTML element, use the statement: document.getElementById(element_id).style.property=new styleExample

Click Me!

DHTML Summary • •

DHTML is about combining HTML, JavaScript, DOM, and CSS. DHTML is a Term

In this tutorial you have learned that DHTML is only a term used to describe the different combinations of HTML, JavaScript, DOM, and CSS that can be used to create more dynamic web pages. More DHTML examples JavaScript JavaScript is the standard scripting language for the Internet. Everyone serious about web development should have a full understanding of JavaScript. The HTML DOM HTML 4 supports the HTML Document Object Model (DOM). The HTML DOM is the official (standard and browser independent) way to access HTML elements. It works in all browsers. Only by using the HTML DOM you can make interactive web pages that will work in all modern browsers. Dynamic CSS There is no such thing as dynamic CSS. However, with JavaScript and the HTML DOM you can dynamically change the CSS style of any HTML element. Server Side Scripting In this tutorial you have seen that web pages can be made dynamic by using scripts on the client (in the browser). Web pages can also be made more dynamic by using scripts on the server. With server scripting you can edit, add, or change any web page content. You can respond to data submitted from HTML forms, access data or databases and return the results to a browser, and customize pages for individual users. At W3Schools you can study the following server side scripting tutorials: • PHP tutorial • ASP tutorial • DotNET tutorial