Chapter 4 HTML. Objectives Explain how HTML/XHTML are used and describe the difference between them Interpret HTML code Explain how HTML Forms are used.

Chapter 4HTML

Objectives

• Explain how HTML/XHTML are used and describe the difference between them

• Interpret HTML code• Explain how HTML Forms are used in web

applications• Interpret HTML Forms• Explain the purpose Cascading Style Sheets

(CSS)• Describe the different formats for CSS code• Interpret CSS code

HTML

• HyperText Markup Language (HTML) is the language for writing web pages

• HTML/4 is the current version

• HTML/4 versions include– strict: strictly enforces syntax rules– traditional: allows informally accepted syntax– frameset: allows the use of HTML frames

XHTML

• XHTML is HTML expressed as an XML document

• Compared to HTML– XHTML has a more rigorous syntax, which is

more machine-readable– XHTML contains more meta-information, i.e.,

information about the HTML document

HTML Syntax

• Each HTML element is defined by a tag, or pair of tags– tags are delimited by angle brackets: < >– tags may include attributes( name=“value” )

• Paired tags have content– e.g., paragraph: <p>Hello!</p>

• Empty tags contain nothing– e.g., <br />, <img src=“ball.jpg” alt=“Ball” />

Sample Web Page

XHTML Headings

• XHTML documents start in this form(version XHTML/1-strict)

<?xml version="1.0" encoding="UTF-8"?>

<!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" lang="en">

define XML version

define XML documenttype

startHTMLdocument

<head> element

• The first element of an HTML document is the <head> element– defines a document title, among other things– document title appears in the browser title bar

<head> <title>Eastern Hills Soccer League</title></head>

Headings and Paragraphs

<h1>Eastern Hills Soccer League</h1>

<hr />

<p><img src="SoccerBall.jpg" alt="Soccer Ball"/></p>

<p><strong>EHSL Mission:</strong> to serve allchildren in the Hills area by providing anopportunity for them to grow up healthy, happy, andstrong through participation in the world's greatestcompetitive sport.</p>

heading, level1(1-6 available )

horizontal rule

image

paragraph (text)

Lists

• <ul> unordered (bullet) list

• <ol> ordered (numbered) list

• <li> list item

<ul> <li> <a href="standings.html">Current Team

Standings</a></li> <li><a href="matches.html">This Week's Matches</a></li> <li><a href="mailto:[email protected]">Contact Us</a></li></ul>

Hyperlinks

• Hyperlinks take the browser to other documents when clicked

• Format:<a href=“ …url … “> …link text… </a>

– e.g., <a href="standings.html">Current Team Standings</a>

Tables

• An HTML table presents data in a grid format

<table border=“1”> <caption>Table Caption</caption> <tbody> <tr> <td>R1,C1</td> <td>R1,C2</td> <td>R1,C3</td> </tr> <tr> <td>R2,C1</td> <td>R2,C2</td> <td>R2,C3</td> </tr> </tbody></table>

R1,C1 R1,C2 R1,C3

R2,C1 R2,C2 R2,C3

Table Caption

HTML Forms

• An HTML Form presents a fill-in form for entering data

• Form controls include– text box, text area, and password box– check box– radio buttons– drop-down menus– submit buttons

Form tag

Text and Passwords

Check-box and Radio-Buttons

Drop-Down Menus

Submit Buttons

CSS

• Cascading Style Sheets is a technique for changing the appearance, or style, of web page elements

• Style may be defined in three ways:– in-line: along with an HTML

element– internal style sheet: within an HTML document– external style sheet:outside of an HTML document

Style Elements

• The “style” of an element can include many visible attributes:– Color– Size– Font– Alignment– Decoration (underline, bold, etc.)– etc.

Style Definition

• Style attributes are defined as a set of “name: value” pairs, separated by “;”

color: red; background: blue; align: left

• Each HTML element has its own set of relevant style attributes

In-Line Style

• In-line style is defined using the “style” attribute of an HTML element

<p style=“color: blue; text-align: center”>This paragraph is centered in blue</p>

This paragraph is centered in blue

Internal Style Sheet

• An internal style sheet is defined in the heading of an HTML document– Delimited by <style type=“text/css”>…</style>

<head> <title>...</title> <style type=“text/css”> p { color: blue; text-align: center } </style></head>


• An internal style sheet consists of a set of descriptors

• Each descriptor defines the style for one HTML element

• Descriptor format:

h1 { text-align: center; color: brown }

selector declaration block

property name / value


h1 { text-align: center; color: brown }

• The selector identifies one or more HTML elements to which the rule applies– multiple elements are comma-separated

• Property values in the declaration block apply to each instance of the selected HTML element(s)

selector declaration blockproperty name / value

Selectors

• Descriptors starting with "." define classes that can be referenced in document elements using the class attribute

.number { text-align: right }

<p class="number">1234</p>

Selectors

• Descriptors may also identify established psuedoclasses– e.g., a:hover is applied to hyperlinks only

while under the cursor

a:hover { background: white }

Internal Style Sheet Example

<head> <title>...</title> <style> h1 { color: brown; background-color: lightgray; border: solid gray; text-align:center; padding: .5em; } .strong { font-weight: bold; } .quote { margin-left: 1em; margin-right: 1em; } li { padding-top: 1ex; } a:hover { background-color: lightgray; } </style></head>

External Style Sheet

• An external style sheet has the same format as an internal style sheet, but is stored in a separate document

• It is imported into a document with a <link> tag

<head> ... <link rel="stylesheet" type="text/css"

ref="styles/style-1.css"></head>

CSS - Precedence

• When conflicting style attributes apply to an element, the closest one takes precedence

ExternalStyleSheet Internal

StyleSheet In-line

StyleAttribute

HTMLElement

Review

• HTML

• XHTML

• HTML Forms

• Cascading Style Sheets

• In-line, internal, and external style sheets

Chapter 4 HTML. Objectives Explain how HTML/XHTML are used and describe the difference between them Interpret HTML code Explain how HTML Forms are used.

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