Glossary

Absolute URI

See URI.

Accessibility

Making sure a website is useable by as many people as possible. This includes overcoming various handicaps such as blindness.

Ancestor Element

The element that another element is nested within. For example, all elements are nested within the root element, so the root element is the ancestor element of everything. Another example is the body element is an ancestor of all p elements. A parent element is a more specific type of ancestor element.

Ancestry

Which element is nested within which.

Array

A variable that can store multiple values.

Attribute

Extra coding that contains additional information about an element. Attributes have this syntax: attribute_name="attribute_value". There are a number of special types of attributes:

Text

These attributes can contain any kind of text. Some require text to be in a special format to be of use such as href, which requires the text to be a hyperlink.

ID

These attributes type needs to be a single word unique within the document.

ID Reference

These attributes should contain a space-seperated list of IDs existing within the document.

Enumerated

These attributes have a predefined list of possible values.

Boolean

These attributes have a single legal value. Their real value is their presence or absence (see Boolean).

Permitted attributes fall into two broad catagories:

Required

According to the rules of the markup language, these attributes must be included in the start tag.

Implied

According to the rules of the markup language, these attributes may be included in the start tag.

Attributes that are neither required nor implied may not be used in the start tag. There are three groups of very common attributes. The groups are:

Core Attributes

Attributes allowable in almost every element. The core attributes are: class, id, style, and title

Language Attributes

Attributes that deal with the language of an element's content. The language attributes are lang and dir

Event Attributes

Attributes that trigger dynamic behavior through a script. The event attributes are: onclick, ondblclick, onmousedown, onmouseup, onmouseover, onmousemove, onmouseout, onkeypress, onkeydown, and onkeyup.

Block Element

An element that breaks text or other content into a two-dimensional block. An example is the p element, which is used to create paragraphs.

Boolean

In programming, a type of value that is either true or false. In JavaScript, true and false are predefined values, and conditions for while loops and if statements are always ultimately boolean in nature. In HTML, boolean attributes are true if included, and false if omitted. They have one possible value, which is exactly the same as their name (for example, checked="checked", nohref="nohref", defer="defer").

Box Model

The box model is the area around an element's content. It comprises (from inside out) padding, border, and margin.

Browser

The Program you use to view a webpage. Examples are: Internet Explorer, Mozilla Firefox, Opera, Safari, Konqueror, Netscape, and Lynx (a text-only browser).

Calling

Making a reference to a procedure, thus using the code contained therein.

Cascading Style Sheet

For the language, see CSS. For the file, see Stylesheet.

Character Reference

The code starting with an ampersand (&) and ending with a semicolon (;) that refers to a character, usually used for characters that do not appear on the keyboard the coder is using. There are two types of character references:

Numerical character references

NCR for short. These use numbers corresponding with characters in UNICODE or similar systems. The numbers are preceded with # for decimal codes and #x for hexadecimal codes.

Character entity references

These are character references named in the DTD and associated with a numerical character reference.

Child Element

An element nested immediately within another. For example, p elements can only have inline elements as child elements. Likewise, ol and ul elements must have li elements as child elements.

Client-Side Scripting

See Dynamic Behavior and Scripting Language.

Code

The text a browser interprets in order to display the webpage. Unlike content, you don't see the code on the screen; you see its effects instead. In this book, code usually refers to HTML, CSS, or JavaScript.

Code Bloat

A phenomenon when the code takes up a significant portion of the file. In many cases, the amount of code overwhelms the amount of content.

Comment

Code or content that has absolutely no bearing on the rendering of the page. This can be used to set aside code intended to be copied or amended later or text that describes the portions of the document.

Multi-Line Comment Syntax

Language	Starts With	Ends With
HTML	<!--	-->
CSS	/*	*/
JavaScript	/*	*/

JavaScript also has a single-line comment that starts with //.

Concatenation

Joining two strings of text into one. In CSS, this is achieved by simply following one string with another. In JavaScript, the concatenation operator is +.

Content

What you want to display on the Internet via your webpage. It can be:

• text such as stories or information,
• images such as diagrams or artwork,
• animations or movie clips
• sound files such as music or spoken instructions

or any other media you can think of. Essentially, it's what you see on your computer screen (with the exception of sound files, obviously). The display of content is (or at least should be) the entire point of a website.

Core Attributes

See Attributes.

CSS

Cascading Style Sheets. A computer language designed to handle the formatting (that is, the appearance) of a webpage.

Declaring A Variable

Using the keyword var to tell the browser that a JavaScript variable now exists. A value may or may not be assigned.

Declaration

In CSS, a bit of code that selects and controls an aspect (such as the border, padding, or text alignment) of an element's appearance.

Definition List

See List.

Deprecated

Refers to an element meant to be phased out of use, but is still part of a transitional DTD. Most presentational elements are deprecated in HTML.

Descendant Element

An element nested somewhere within another, either as a child element or nested deeper with in. For example, all elements are descendants of the root element, except (of course) the root element itself. A child element is a more specific variant of a descendant element.

Doctype

Full name: Document Type Declaration. A piece of coding that is placed at the very top of the page, outside the root element. Its purpose is to declare the type of markup language being used. The HTML 4.01 Strict Doctype is:

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">

Document

An actual file. For example HTML document or CSS document.

Document Tree

A chart or map of which elements are nested in which.

DOM

Document Object Model. A chart or map of a webpage's elements, nesting, attributes, and contents.

Domain

The address of a website. This usually follows the protocol.

DTD

Full name: Document Type Definition. A document that lays out the rules of a markup language. The HTML 4.01 Strict DTD can be found at http://www.w3.org/TR/html4/strict.dtd.

Dynamic Behaviour

When a user can interact with the page.

Element

A component of an HTML document. Elements can contain information about the document, references to other resources, content, and/or other elements.

Element Name

A word made up of letters (and sometimes numbers as well) that identify element's type. Examples in HTML are p (for a paragraph), ul (for an unordered list), and h1 (for a first-level header).

em

In CSS, a length based on a font's em-box, which is a theoretical square that sets the size of a font. For example, 1.2em is equal to 1¹/₅ the length of a single em-box.

Email Hyperlink

A hyperlink that contains mailto: followed by an email address. This kind of hyperlink usually launches an email program.

Empty Element

An element with no content, and thus consists only of a start tag. All information that can pertain to these elements is contained within the start tag.

Event

A way in which the user interacts with the page (other than clicking on a hyperlink). It could be changing the value on a form, clicking on an element, or moving a mouse. The events are: onclick, ondblclick, onmousedown, onmouseup, onmouseover, onmousemove, onmouseout, onkeypress, onkeydown, and onkeyup

ex

In CSS, a length based on the height of a font's lower-case x.

External Stylesheet

A stylesheet contained in a seperate file.

For Loop

See Loops

Form

A collection of elements that allow you to enter data into a webpage for processing either client-side or server-side. Both client-side and server-side scripting languages are often specially designed to read forms.

Formatting

See Presentation

Frames

In HTML, a means of breaking up the viewport of a window to allow multiple pages to be shown.

Frameset

In HTML, a variant of HTML 4.01 and XHTML 1.0 that allows the use of frames.

Function

In JavaScript, a procedure that stands on its own.

Hexadecimal

Base 16. It uses the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F. Hexadecimal (Hex for short) is used in UNICODE codes (which means its used for special characters in HTML, CSS, and JavaScript) and CSS colors.

HTML

HyperText Markup Language. The language used to structure the content of webpages.

If Statement

In JavaScript, a construct that decides whether or not a set of instructions are executed based on circumstances described in its condition. An if statement may have options using else if (an alternative based on other conditions) and else (a default alternative). HTML also has an if statement, but that is supported by Internet Explorer only.

Image Map

A construct that allows part of an image to be used as a hyperlink. Many such maps specify multiple areas as links to different pages.

Inline Element

An element that does not cause the text flow to break. For example, the strong element highlights text, but otherwise has no affect on the text flow.

Inline Frames

In HTML, a means of showing one page within another. This can be mimicked using the object element.

Inline Styling

Applying CSS to a specific element through the style attribute.

Internal Stylesheet

A stylesheet contained in the webpage itself.

Instance

In JavaScript, each object that has been created through a template is known as an instance of that template.

Instantiate

In JavaScript, to create an object using a template.

JavaScript

The most popular scripting language. The Internet Explorer version is known as JScript. Despite rumours, has very little to do with Java.

Language Attributes

See Attributes.

List

A collection of items. There are three types:

Definition

A list of terms and explanations.

Ordered

A list with an implied sequence.

Unordered

A list with no implied sequence.

Loop

A set of instructions that are run repeatedly so long as a certain condition is met. If the condition is always met, with no possibility of it proving false, that is an infinite loop. There are two main types

for

How often this type of loop is run is specifically stated in its condition.

while

This type of loop is run until its condition is no longer met.

Meta-Language

In web development, a markup language used to create other markup languages. XML is a meta-language.

Method

In JavaScript, a procedure that is part of an object.

Namespace

In XML, a string of text (usally an URI) that acts as an identifire for a markup language.

Nesting

Placing one element within another. The inner element must be contained completely within—that is, begin after and end before—the outer element.

Node

The building blocks of a DOM. Types of nodes are document, element, attribute, and text.

Node Tree

A chart of how the various nodes are related to each other.

Object (HTML)

An element that allows the display of content other than images or text. This is required for embedding sound files, movies, SVG images, and other webpages.

Object (JavaScript)

A collection of values and functions.

Obsolete

In HTML, an element not in use in any modern DTD. These elements may not be supported by a browser.

Octal

Base 8. It uses the digits 0, 1, 2, 3, 4, 5, 6, 7. Octal may be used for special characters in Javascript.

Operator

A special symbol or sequence of symbols in a programming language (including scripting languages) which tells the program to do something. For example, = assigns a value to a variable in JavaScript and many other languages, while == checks to see whether or not two values are equal.

Ordered List

See List.

Parameter

In HTML objects, this allows for certain aspects of the embedded content, such as automatic playback or the quality of a flash movie, to be controlled.

Parent Element

The element that another element is nested immediately within. For example, the head element is the parent of a title element.

Path

The sequence of folders that a browser must look through to find a folder. Three folders used in relative URI have special names:

/

The root folder

./

The current folder.

../

The parent folder.

pc

Abbreviation for pica, which is ¹/₆ of an inch.

Phrase Element

Elements that set apart certain phrases to give them special meaning. Most of these elements alter the appearance of their content to suggest its semantic meaning.

Pixel

A single dot on a screen. A screen with an 800X600 resolution is 800 pixels across and 600 pixels tall. The actual, physical measurement of the screen is irrelevent.

Presentation

How the webpage and its content look.

Presentational Element

Elements that alter the appearance of an element regardless of semantics. These elements are being phased out.

Print-Friendly Page

A page with its design simplified so that printers can print it without wasting ink or paper. Common with pages that use presentational markup.

Procedure

In JavaScript, a set of programming instructions that are grouped together and placed in a special block so they can be used without having to retype the instructions, simply refer to the set.

Property (CSS)

An aspect of an element that is being controlled by a CSS declaration.

Property (JavaScript)

Part of an object that holds a value.

Proprietary Markup

Non-standard markup that only one browser can read. This was very common during the competition between Netscape and Internet Explorers (called the Browser Wars).

Protocol

A standardized means of communication between computers in a network. The protocol most often used on the World Wide Web is HyperText Transfer Protocol, which allows webpages to be downloaded by computers.

PT

Abbreviation for point, which is ¹/₇₂ of an inch.

Relative URI

See URI.

Render

To display a webpage or part of a webpage.

Rickroll

A link to the music video of Rick Astley's song Never Gonna Give You Up that purports to lead elsewhere. Also, to post such a link or to be deceived by one. For example, the link that has the title Click here for the definition of Rickroll in HTML Objects is (or was, if the link is out of date) itself a Rickroll.

Root Element

The outermost element, or the element with all the webpage's content and elements nested within it.

Rule

In CSS, the building blocks of a stylesheet. They contain a selector (which tells which elements are targeted by the rule) and declarations, which describe how each targeted element should look.

Scripting Language (Client-side)

A programming language that allows the user to interact with the page. Popular scripting languages are JavaScript (which is explained in this book) and VBScript (which is not).

Selector

In CSS, selectors tell the browser which elements should have a rule applied to them. Types of selectors are:

Universal

The symbol is *. It selects everything.

Type

Selects by element name.

Class

Begins with ., and selects according to the class attribute.

ID

Begins with #, and selects according to the id attribute.

Pseudo-Class

Begins with :, and selects according to aspects outside the DOM.

Pseudo-Element

Begins with : in CSS 2.1, :: in CSS 3. Selects elements not found in the document or DOM.

Attribute

Selects according to the attribute's presence or even value. Begins with [ and ends with ].

Semantics

The meaning of an element, or precisely what it is used for. For example, em elements are used to emphasize something, but dfn elements are used to denote a definition.

Sibling Element

An element that shares the same parent as another. For example, both the head and body elements have the html element for a parent, therefore head and body are sibling elements.

Strict

In HTML, a variant of HTML 4.01 and XHTML 1.0 that does not allow the use of any element meant to be phased out.

String

A piece of text. Usually used when talking about CSS or JavaScript (especially the latter).

Stylesheet

A means of providing formatting to a webpage. The most common stylesheet language used with HTML is CSS. Stylesheets are either contained within the style element or in a seperate document referred to through a link element, both children of the head element.

SVG

Scalar Vector Graphics, an XML-based language for creating graphics.

Switch Statement

A decision construct that executes one of multiple sets of instructions based on an enumerated list of specific circumstances.

Table

An HTML construct that allows information to be displayed on a grid, as if the page had an embedded spreadsheet.

Tag

A piece of HTML code that marks the boundaries of an element. There are two types of tags: start tags and end tags. Tags contain the element name and that element's attributes (if it has any), begin with the symbol < and end with >. A slash (/) before the element name makes a tag an end tag. Start tags have no slash.

Tag Soup

See Code Bloat.

Template

A procedure that assigns values and methods to one or more variables, thus making that variable a JavaScript object. Every object created through a template will have the same properties; but they do not need to have the same values.

Text-Only Browser

A now-rare type of browser that displays just the text of a webpage, and nothing more. Images, styling, and scripts are not supported by these.

Transitional

In HTML, a variant of HTML 4.01 and XHTML 1.0 that allows the use of deprecated elements and attributes.

UNICODE

A system of encoding characters in writing systems around the world, with the intention of making the World Wide Web truly international.

Unordered List

See List.

URI

Universal Resource Indicator; a pointer to a resource on the Internet. A URL (Universal Resource Locator) is a type of URI. There are two types of URI:

Absolute

A URI with the protocol included. This will tell the browser the exact location of the desired resource. This is required used when the resource is on another website or uses a different protocol.

Relative

A URI with the protocol omitted. The browser will look for the resource relative to the current page, or relative to the absolute URI contained in the base element.

User Agent

A program used for communicating over a network. The most common type—at least as far as the World Wide Web is concerned,—is a browser, though this also covers speech synthesizers and other programs that read webpages.

Validation

Making sure that your HTML and CSS follows the rules set down for them, minimizing the chance for improper or inconsistent rendering. The HTML validator is at http://validator.w3.org/, while the CSS is at http://jigsaw.w3.org/css-validator/.

Value (CSS)

How an aspect of an element that is being controlled by a CSS declaration is made to appear (for example, if the aspect is the colour of a border, the value may be red).

Value (JavaScript)

Information held in a variable. The value can be a number, a string of text, a node, an object, or so on.

Variable

In JavaScript, a means of storing and referring to a changeable value.

Webpage

What your browser displays.

While Loop

See Loops

Whitespace

New lines, tab characters, and spaces.

World Wide Web

The area of the Internet which is used for webpages.

XHTML

eXtensible Hypertext Markup Language. HTML rewritten as an XML language.

XML

Extensible Markup Language. This is a meta-language that requires all elements to be explicitely closed, all character reference codes to be properly coded, and all attributes to be fully written out and quoted.