06-11-2012, 01:51 PM
Introduction to Web Technologies
Web Technologies.ppt (Size: 722.5 KB / Downloads: 461)
Presentation Overview
Look at main technological components that make up modern Web pages
HTML – HyperText Markup Language
CSS – Cascading Style Sheets
JavaScript – um, JavaScript
For each component
What it is/isn't, can/can't do
What kinds of constructs it comprises
How to use it in Web pages
How it interacts with other components
HTML Components
Documents
Document = page = HTM file = topic
Content (text, images)
Tags (display commands)
Other terms
Window: browser display window
URL: Uniform Resource Locator
Hyperlink: hypertext jump to a resource
Resource: URL, image, mailto, external file
HTML Pages
HTML pages are tag-based documents
Really plain ASCII text files
Don't look like documents they represent
Tags indicate how processing program should display text and graphics
Designed to describe hypertext, not paper
Processed by browsers "on the fly"
Tags usually appear in pairs
Most have reasonable names or mnemonics
Most can be modified by attributes/values
What's "Cascading" All About?
Three places to put style commands
External: Affects all documents it's attached to
Internal: Affects only document it appears in
Inline: Affects only text it's applied to
Cascading means styles' "pecking order"
Precedence is: Inline > Internal > External
Seems backward, but it couldn't work any other way; for example…
Picture a document whose style sheet specifies Verdana as the font, with one paragraph style in Courier New, with one bold word or phrase
Programming Constructs
Variables
Named elements that can change value
Data types
Integer, floating-point, Boolean, string
Operators
Assignment, comparison, arithmetic,Boolean, string, special
Control statements
Conditions, loops
Keywords
Reserved words with special meaning