DHTML Tutorial

DHTML Tutorial 2

Contents

DHTML Tutorial DHTML Intro DHTML CSS DHTML DOM DHTML Events DHTML Summary

DHTML DOM

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DOM Reference

DHTML is the art of making HTML pages dynamic! DHTML is a combination of technologies used to create dynamic and interactive Web sites. To most people DHTML means a combination of HTML, Style Sheets and JavaScript.

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Introduction to DHTML What you should already know Before you continue you should have a basic understanding of the following: • • •

HTML CSS  JavaScript

If you want to study these subjects first, find the tutorials on our Home Page.

DHTML is NOT a W3C Standard DHTML stands for Dynamic HTML. DHTML is not a standard defined by the World Wide Web Consortium (W3C). DHTML is a "marketing term" used by Netscape and Microsoft to describe the new technologies the 4.x generation browsers would support. DHTML is a combination of technologies used to create dynamic Web sites.  To most people DHTML means a combination of HTML 4.0, Style Sheets and JavaScript. W3C once said: "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 With DHTML a Web developer can control how to display and position HTML elements in a browser window.

HTML 4.0 With HTML 4.0 all formatting can be moved out of the HTML document and into a separate style sheet. Because HTML 4.0 separates the presentation of the document from its structure, we have total control of  presentation layout without messing up the document content.

Cascading Style Sheets (CSS) With CSS we have a style and layout model for HTML documents. CSS was a br eakthrough in Web design because it allowed developers to control the style and layout of  multiple Web pages all at once. As a Web developer you can define a style for each HTML element and apply it to as many Web pages as you want. To make a global change, simply change the style, and all elements in the Web are updated automatically.

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DHTML Tutorial The Document Object Model (DOM)

4 DOM stands for the Document Object Model.  The HTML DOM is the Document Object Model for HTML.  The HTML DOM defines a standard set of objects for HTML, and a standard way to access and manipulate HTML objects. "The W3C Document Object Model (DOM) is a platform and language neutral interface that allows programs and scripts to dynamically access and update the content, structure, and style of a document" .

 JavaScript Allows you to write code to control all HTML elements.

DHTML Technologies in Netscape 4.x and Internet Explorer 4.x Netscape 4.x •

Cross-Browser DHTML

 JSS (JavaScript Style Sheets) (allows you to control how different HTML elements will be displayed)

• •

• •

Layers (allows you to control element positioning and visibility) •

CSS1 CSS2 (allows you to control how different HTML elements will be displayed) CSS Positioning (allows you to control element positioning and visibility)

Internet Explorer 4.x •

Visual Filters (allow you to apply visual effects to text and graphics)

•

Dynamic CSS (allows you to control element positioning and visibility)

 JavaScript

Note: Problems with coding DHTML technologies WILL occur as long as each browser creates its own proprietary features and technology that is not supported by other browsers. A Web page may look great in one browser and horrible in another.

DHTML CSS Positioning (CSS-P) CSS is used to style HTML elements.

Examples Note: Most of the DHTML examples require IE 4.0+, Netscape 7+, or Opera 7+!

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DHTML Tutorial position:relative How to position an element relative to its normal position.

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position:relative How to position all headings relative to their normal position.

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DHTML Tutorial position:absolute How to position an element using an absolute value.

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Which Attributes can be Used with CSS-P? First, the element must specify the position attribute (relative or absolute).  Then we can set the following CSS-P attributes: • • • • • •

left - the element's left position top - the element's top position visibility - specifies whether an element should be visible or hidden z-index - the element's stack order clip - element clipping overflow - how overflow contents are handled

Position  The CSS position property allows you to control the positioning of an element in a document.

position:relative  The position:relative property positions an element relative to its current position.  The following example positions the div element 10 pixels to the right from where it's normally positioned :

div { position:relative; left:10; }

position:absolute  The position:absolute property positions an element from the margins of the window.

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DHTML Tutorial  The following example positions the div element 10 pixels to the right from the left-margin of its containing block :

div { position:absolute; left:10; }

Visibility  The visibility property determines if an e lement is visible or not.

visibility:visible  The visibility:visible property makes the element visible.

h1 { visibility:visible; }

visibility:hidden  The visibility:hidden property makes the element invisible.

h1 { visibility:hidden; }

Z-index  The z-index property is used to place an element "behind" another element. Default z-index is 0. The higher number the higher priority. z-index: -1 has lower priority.

h1 { z-index:1; } h2 { z-index:2; } In the example above, if the h1 and h2 elements are positioned on top of each other, the h2 element will be positioned on top of the h1 element.

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DHTML Tutorial Filters

8  The filter property allows you to add more style effects to your text and images.

h1 { width:100%; filter:glow; } Note: Always specify the width of the element if you want to use the filter property.  The example above produces this output:

Header Different Filters Note: Some of the Filter properties will not work unless the background-color property is set to transparent! Property

Argument Description

Example

alpha

opacity Allows you to set the opacity of the element finishopacity style startx starty finishx finishy

filter:alpha(opacity=20, finishopacity=100, style=1, startx=0, starty=0, finishx=140, finishy=270)

blur

add direction strength

Makes the element blur

filter:blur(add=true, direction=90, strength=6);

chroma

color

Makes the specified color transparent

filter:chroma(color=#ff0000)

fliph

none

Flips the element horizontally

filter:fliph;

flipv

none

Flips the element vertically

filter:flipv;

glow

color strength

Makes the element glow

filter:glow(color=#ff0000, strength=5);

gray

none

Renders the element in black and white

filter:gray;

invert

none

Renders the element in its reverse color and brightness values

filter:invert;

mask

color

Renders the element with the specified background color, and transparent foreground color

filter:mask(color=#ff0000);

shadow

color direction

Renders the element with a shadow

filter:shadow(color=#ff0000, direction=90);

Renders the element with a dropshadow

filter:dropshadow(color=#ff0000,

dropshadow color

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DHTML Tutorial offx offy positive

offx=5, offy=5, positive=true);

wave

add Renders the element like a wave freq lightstrength phase strength

filter:wave(add=true, freq=1, lightstrength=3, phase=0, strength=5)

xray

none

filter:xray;

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Renders the element in black and white with reverse color and brightness values

Background  The background property allows you to select your own background.

background-attachment:scroll  The background scrolls along with the rest of the page.

background-attachment:fixed  The background does not move when the rest of the page scrolls.

More Examples Visibility How to make an element invisible. Do you want the element to show or not?

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DHTML Tutorial Z-index Z-index can be used to place an element "behind" another element, using Z-index priority.

Z-index Check that the elements now have changed their Z-index priority.

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DHTML Tutorial Cursors Change the style of the mouse cursor with CSS.

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Filters Change the style of your headings using the filter property.

Filters on Images  The filter property can also be used on images, here are some filter examples which look good on images.

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DHTML Tutorial Watermark A background picture that does not move when the rest of the page is scrolling.

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DHTML Document Object Model The Document Object Model gives us access to every element in a document.

Examples Note: Most of the DHTML examples require IE 4.0+, Netscape 7+, or Opera 7+! Element access How to access an element and change the style.

Attribute change How to access an image element and change the "src" attribute.

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DHTML Tutorial innerHTML How to access and change the innerHTML of an element.

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How to access an element?  The element must have an id attribute defined and a scripting language is needed. JavaScript is the most browser compatible scripting language, so we use JavaScript.

My header

<script type="text/javascript"> document.getElementById('header').style.color="red";  The script changes the color of the header element, and produces this o utput.

My header

DHTML Event Handlers With an event handler you can do something with an element when an event occurs.

Examples Note: Most of the DHTML examples require IE 4.0+, Netscape 7+, or Opera 7+! onmouseover & onmouseout How to change the color of an element when the cursor moves over and out of an element.

onclick  Turn on the light! How you can change an image when you click on it, and back to the original image when you click on it again.

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After clicked over the light….

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DHTML Tutorial onmousedown & onmouseup  This time the light is on only when you hold the mouse button down.

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onload Displays an alert box when the page has finished loading.

Event handlers With an event handler you can do something with an element when an event occurs: when the user clicks an element, when the page loads, when a form is submitted, etc.

Click on this text

 The example above defines a header that turns red when a user clicks on it.  You can also add a script in the head section of the page and then call the function from the event handler:

<script type="text/javascript"> function changecolor()

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DHTML Tutorial { document.getElementById('header').style.color="red"; }

Click on this text

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HTML 4.0 Event Handlers Event

Occurs when...

onabort

a user aborts page loading

onblur

a user leaves an object

onchange

a user changes the value of an object

onclick

a user clicks on an object

ondblclick

a user double-clicks on an object

onfocus

a user makes an object active

onkeydown

a keyboard key is on its way down

onkeypress

a keyboard key is pressed

onkeyup

a keyboard key is released

onload

a page is finished loading. Note: In Netscape this event occurs during the loading of a page!

onmousedown

a user presses a mouse-button

onmousemove

a cursor moves on an object

onmouseover

a cursor moves over an object

onmouseout

a cursor moves off an object

onmouseup

a user releases a mouse-button

onreset

a user resets a form

onselect

a user selects content on a page

onsubmit

a user submits a form

onunload

a user closes a page

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DHTML Tutorial  You Have Learned DHTML, Now What?

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DHTML Summary  This tutorial has taught you how to use DHTML to create more dynamic and interactive Web sites.  You have learned how to use the combination of HTML, CSS and JavaScript to animate HTML documents. For more information on DHTML, please look at our DHTML examples and our DHTML reference.

Now You Know DHTML, What's Next?  The next step is to learn about the HTML DOM and ASP.

HTML DOM  The HTML DOM defines a standard way for accessing and manipulating HTML documents.  The HTML DOM is platform and language independent and can be used by any programming language like  Java, JavaScript, and VBScript. If you want to learn more about the DOM, please visit our HTML DOM tutorial.

ASP While scripts in an HTML file are executed on the client (in the browser), scripts in an ASP file are executed on the server. With ASP you can dynamically edit, change or add any content of a Web page, respond to data submitted from HTML forms, access any data or databases and return the results to a browser, customize a Web page to make it more useful for individual users. Since ASP files are returned as plain HTML, they can be viewed in any browser. If you want to learn more about ASP, please visit our ASP tutorial.

DHTML DOM Objects With JavaScript you can access and manipulate all of the HTML DOM objects.

HTML DOM Objects  The HTML DOM is a W3C standard and it is an abbreviation for the Document Object Model for HTML.

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DHTML Tutorial  The HTML DOM defines a standard set of objects for HTML, and a standard way to access and manipulate HTML documents. All HTML elements, along with their containing text and attributes, can be accessed through the DOM. The contents can be modified or deleted, and new elements can be created.  The HTML DOM is platform and language independent. It can be used by any programming language like  Java, JavaScript, and VBScript. Follow the links below to learn more about how to access and manipulate each DOM object with JavaScript:

Object

Description

Anchor

Represents an HTML a element (a hyperlink)

Applet

Represents an HTML applet element. The applet element is used to place executable content on a page

Area

Represents an area of an image-map. An image-map is an image with clickable regions

Base

Represents an HTML base element

Basefont

Represents an HTML basefont element

Body

Represents the body of the document (the HTML body)

Button

Represents a push button on an HTML form. For each instance of an HTML tag on an HTML form, a Button object is created

Checkbox

Represents a checkbox on an HTML form. For each instance of an HTML tag on an HTML form, a Checkbox object is created

Document

Used to access all elements in a page

Event

Represents the state of an event, such as the element in which the event occurred, the state of the keyboard keys, the location of the mouse, and the state of the mouse b uttons

FileUpload

For each instance of an HTML tag on a form, a FileUpload object is created

Form

Forms are used to prompt users for input. Represents an HTML form element

Frame

Represents an HTML frame

Frameset

Represents an HTML frameset

Hidden

Represents a hidden field on an HTML form. For each instance of an HTML tag on a form, a Hidden object is created

History

A predefined object which can be accessed through the history property of the Window object. This object consists of an array of URLs. These URLs are all the URLs the user has visited within a browser window

Iframe

Represents an HTML inline-frame

Image

Represents an HTML img element

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DHTML Tutorial 20 Link

Represents an HTML link element. The link element can only be used within the tag

Location

Contains information about the current URL

Meta

Represents an HTML meta element

Navigator

Contains information about the client b rowser

Option

Represents an option in a selection list on an HTML form. For each instance of an HTML tag in a selection list on a form, an Option object is created

Password

Represents a password field on an HTML form. For each instance of an HTML tag on a form, a Password object is created

Radio

Represents radio buttons on an HTML form. For each instance of an HTML tag on a form, a Radio object is created

Reset

Represents a reset button on an HTML form. For each instance of an HTML tag on a form, a Reset object is created

Screen

Automatically created by the JavaScript runtime engine and it contains information about the client's display screen

Select

Represents a selection list on an HTML form. For each instance of an HTML tag on a form, a Select object is created

Style

Represents an individual style statement. This object can be accessed from the document or from the elements to which that style is applied

Submit

Represents a submit button on an HTML form. For each instance of an HTML tag on a form, a Submit object is created

 Table

Represents an HTML table element

 TableData

Represents an HTML td element

 TableHeader

Represents an HTML th element

 TableRow

Represents an HTML tr element

 Text

Represents a text field on an HTML form. For each instance of an HTML tag on a form, a Text object is created

 Textarea

Represents an HTML textarea element

Window

Corresponds to the browser window. A Window object is created automatically with every instance of a or tag

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