WEB Developer's Glossary



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• background-attachment: CSS Property
The background-attachment property determines whether the background image should scroll along with the elements content. The property value of "scroll" will allow the background image to scroll with the content of the container block. The property value of "fixed" will keep the background image fixed with regards to the viewpoint. Of course, if the containing block does not have a scrolling mechanism, this property is not applicable.
background-attachment:
Value: scroll | fixed | inherit
Initial: scoll
Applies to: all elements
Inherited: no
Percentages: N/A
Media: visual
Computed Value: as specified
Style Group: background
Deprecated: no
Example: body {
   background-color: #ffffff;
   background-image: url("star.png");
   background-repeat: repeat-y;
   background-attachment: fixed;
} /*the background image will not scroll with the containing block*/


• background-color: CSS Property
The background-color property specifies the background color of an element. The background color should contrast with the foreground color when your intent is to render text.
background-color:
Value: <color> | transparent | inherit
Initial: transparent
Applies to: all elements
Inherited: no
Percentages: N/A
Media: visual
Computed Value: as specified
Style Group: background
Deprecated: no
Example: tr { background-color: #cdf0ff }


• background-image: CSS Property
The background-image property specifies the URI (either relative or absolute) of the image to be displayed in the elements background. When using the background-image property, also specifiy the background-color property. The image is rendered on top of the background color. Any transparent areas in the image will reveal the background color.
background-image:
Value: <uri> | none | inherit
Initial: none
Applies to: all elements
Inherited: no
Percentages: N/A
Media: visual
Computed Value: absolute URI or none
Style Group: background
Deprecated: no
Example: body { background-image: url("stars.gif"); background-color: blue; } /*a star in the background*/


• background-position: CSS Property
The background-position property will give the background image it's initial position when a background image is specified. Typically two axis values are provided (horizontal and vertical). Values can be expressed with keywords or with percentages and lengths. The second value is optional but when ommitted, it will default to "center". With non-keyword values, the first value represents the horizontal position and the second value represents the vertical position; otherwise, the keyword determines the relevant axis.
background-position:
Value: [ [ <percentage> | <length> | left | center | right ] [ <percentage> | <length> | top | center | bottom ]? ] |
[ [ left | center | right ] || [ top | center | bottom ] ] | inherit
Initial: 0% 0%
Applies to: all elements
Inherited: no
Percentages: refers to the size of the box itself
Media: visual
Computed Value: for <length>, otherwise a <percentage>
Style Group: background
Deprecated: no
Example: body {
   background-color: #ffffff;
   background-image: url("star.png");
   background-position: 20% 30%;
}


• background-repeat: CSS Property
The background-repeat property will specify whether the image is repeated (tiled), and how. All tiling covers the content, padding and border areas of a box. The two axis related repeat values (repeat-x and repeat-y) will cause repetition in both directions along the relevent axis. The default value for background-position is (0% 0%) or top left; this will cause tiling in only one direction:
  • repeat-y: straight down the page, left side only
  • repeat-x: straight across the page, top side only

background-position:
Value: repeat | repeat-x | repeat-y | no-repeat | inherit
Initial: repeat
Applies to: all elements
Inherited: no
Percentages: N/A
Media: visual
Computed Value: as specified
Style Group: background
Deprecated: no
Example: body {
   background-color: #ffffff;
   background-image: url("star.png");
   background-repeat: repeat-y;
   background-position: center;
} /*the star image will be repeated vertically only in the center of background*/


• background (Shorthand Property): CSS Property
The background property is a shorthand property that will encompass all five of the background properties for the background style group. The property values can be expressed in any order when using the shorthand property. Also, the initial value is used when any of the property values are not explicitly expressed.
background:
Value: background     [ <background-color> || <background-image> || <background-repeat> || <background-attachment> ||
<background-position> ] | inherit
Initial: see individual properties
Applies to: all elements
Inherited: no
Percentages: allowed on "background-position"
Media: visual
Computed Value: see individual properties
Style Group: background
Deprecated: no
Example: body { background: white url("star.png") repeat-y scroll center }


• Background Style Group: CSS Property
The background style group is one of eleven property style groups that help define the total CSS property set. The background properties for this group work the best on the box model and have not been completely defined in all cases for inline elements. With the box model, the background encomposes the content area, the padding area and the border area. Margins are always transparent (not affected by background-color or background-image). The background properties that comprise this group are:

• Backreference: JavaScript RegExp
The JS regular expression feature allows you to use values that were previously matched. These values are called backreferences. Groups within a pattern are given a reference numbers (but only for each group that had a successful match). The same pattern that contains the grouping sub patterns may also contain backreferences. The backreferences are indicated with the meta character "\" (a forward slash). This reference is then followed by a number that indicates the set of parentheses (or group) that captured the value.

• Base URI: Web
The base URI is the URI used to resolve relative references. With HTML, the base URI will be either the address of the BASE element or the address of the current source document. With CSS, resolving relative addresses specified with the <uri> data type will be relative to the immediate style sheet URI. If your style is at the document level or an inline style, then the URI is relative to the current source document containing the style. But, if your style is of an external style sheet, then the URI is relative to the URI of the external style sheet.

• before Selector: CSS Selector
The pseudo-element before selector lets you place generated content before the element's content. This same generated content can then be styled. See selector patterns for formats. This pseudo-element is always specified with the content property.

• Binary Operator: JavaScript Operator
A binary operator is a JS operator with two operands. There is an operand to the left of the operator a another operand to the right of the operator. Some binary operators will actually alter the value of the left-side operand. These operations are said to produce a side-effect. Examples of binary operators that produce side effects are: the shift operators and the assignment operators. Other binary operators merely produce a result where the operands remain unchanged, however, the container expression evaluates to a single value based on the operation.

• Binary Truth Table: Logic
The Binary Truth Table will show the outcome from bitwise logical operations. Typically these operations are for the bitwise AND, bitwise OR and the bitwise XOR.

Bitwise Operator Truth Table For Binary Numbers
Operand 1 operand 2 AND Result OR Result XOR Result
1 1 1 1 0
1 0 0 1 1
0 1 0 1 1
0 0 0 0 0


• Bits and Bytes: Web
A byte consists of 8 bits. A bit represents a binary number and can have two values, 0 or 1. A byte can have 256 values, 0 through 255. Digital electronics and all its manifestations can be reduced down to the values of the bit and the coding schemes used to populate the bytes.

• Bitwise Logical Operator Group: JavaScript Operator
The bitwise operator group are binary operators. They have a "left-to-right" associativity. There operands are or convert to integers. These operators perform there operation with 32-bit binary representation of there integer operands. This group consists of the bitwise AND operator, bitwise OR operator and bitwise exclusive OR operator.

• Bitwise AND Operator: JavaScript Operator
The bitwise AND operator ( symbol: & ) works directly on the binary form of numbers. The bits for each number are lined up and the AND operation is performed. After all bits are altered based on the binary truth table criteria, the resulting number is returned from the AND operation.
The attributes of this operator are:

• Bitwise NOT Operator: JavaScript Operator
The symbol for the bitwise NOT operator is the Tilde ( symbol: ~ ). This unary operator takes a single integer operand. The bitwise not operator negates a number and then substracts 1 from it. So: ~13 becomes -14.
The attributes of this operator are:

• Bitwise OR Operator: JavaScript Operator
The bitwise OR operator ( symbol: | ) works directly on the binary form of numbers. The bits for each number are lined up and the OR operation is performed. After all bits are altered based on the binary truth table criteria, the resulting number is returned from the OR operation.
The attributes of this operator are:

• Bitwise XOR Operator: JavaScript Operator
The bitwise XOR operator ( symbol: ^ ) works directly on the binary form of numbers. The bits for each number are lined up and the exclusive OR operation is performed. After all bits are altered based on the binary truth table criteria, the resulting number is returned from the XOR operation.
The attributes of this operator are:

• Bitwise Shift Operator Group: JavaScript Operator
The bitwise shift operator group are binary operators. They have a "left-to-right" associativity and a precedence of 11. There operands are or convert to integers. These operators shift the bits of the first operand by the number specified in the second operand. This group consists of the left shift operator, right shift operator and unsigned right shift operator.

• Block Statement: JavaScript Statement
The block statement will normally contain more than one statement. It is denoted by a pair of curly braces, that is: { }. The block statement term is synonymous with the compound statement. Block statements can be stand alone but are normally associated with iteration supporting statements such as switch, if, for, and while statements.

• Boolean: JavaScript Term
A boolean is a data item that may have exactly one of two possible values. With JS, the boolean data item values are: true or false. A boolean can be thought of as a "toggle"; that is, it is either "on" or "off". JS supports boolean data with the Boolean class. The Boolean data type is also supported and incorporated into the JS language. Booleans defined with a Boolean literal will acquire the nature and behavior of a Boolean object; they have the quality of a wrapper class.

• Boolean Class: JavaScript Class
The Boolean class is a JS Native Class that supports the JS Boolean data type. Object instances of the Boolean class type have access to the properties and methods of the Boolean class. Variables with the Boolean data type adopt the nature and behavior of a Boolean object. See our link for class for the distinction between the terms "class" and "object".

• Boolean Literal: JavaScript Literal
The Boolean literal can have exactly two values; true or false. The JS interpreter requires one of these two literal values to determine the appropriate data type. Other than the two values, literal syntax does not play any further role in the weak typing process the interpreter uses to determine a Boolean type.

• Boolean Object: JavaScript Object
The Boolean object is a instance of the Boolean class type. Object instances of the Boolean class type have access to the properties and methods of the Boolean class. A Boolean object can be declared and initialized by either the Boolean class constructor or by a Boolean literal statement. See our link for class for the distinction between the terms "class" and "object".

• Boolean Operand: JavaScript Operator
The boolean operand is used with a boolean operator. The boolean operand is evaluated by the boolean operator to be either true or false. The boolean operand can be an expression or the keywords true and false.

• Boolean Truth Table: JavaScript Object
The Boolean Truth Table will show the outcome from boolean logical operations. Typically these operations are for the logical AND, logical OR and the logical XOR. Note that JS does not have a logical XOR operator.

Logical Operator Truth Table For Booleans
Operand 1 operand 2 AND Result OR Result XOR Result
true true true true false
true false false true true
false true false true true
false false false false false


• Boolean Type: JavaScript Data Type
The type Boolean represents a logical entity and consists of exactly two unique values. One value is true and the other is called false. The Boolean type is a data type that is associated with the Boolean class. The Boolean type belongs to the primitive type group.

• Boolean Values: JavaScript Data
A boolean value of the type Boolean and is one of two unique values, true and false. Other computer languages use 1 or 0 for the boolean values. Programmers use boolean logic to control loop and express logical comparisons. It may help to think of boolean tests in terms of "on or off" or maybe "yes or no" instead of true or false.

• Border Shorthand Properties: CSS Property

• border, border-top, border-right, border-bottom, border-left:
This set of shorthand properties specify the width, style and color of the top, right, bottom and left border of the box. The border shorthand property will do it all, that is, all three affects (color, style, width) and all four edges (top, right, bottom, left). The other four border shorthand properties will do all of the affects but only to a given edge. The property definition is the same for all five of the following border shorthand properties.
border, border-top, border-right, border-bottom, border-left:
Value: [ <border-width> || <border-style> || <border-color> ] | inherit
Initial: see individual properties
Applies to: all elements
Inherited: no
Percentages: N/A
Media: visual
Computed Value: see individual properties
Style Group: box
Deprecated: no
Example: div {   border-top: thin double blue; /*applies width, style and color to top edge*/   border-right: thin double blue; /*applies width, style and color to right edge*/   border-bottom: thin double blue; /*applies width, style and color to bottom edge*/   border-left: thin double blue; /*applies width, style and color to left edge*/ } and   div { border: thin double blue } /*applies width, style and color to all edges of container*/

Remember there are three other border shorthand properties (border-color, border-style and border-width). These other three shorthand properties are shown separately because there property definitions are not the same as above.

• Border Color Properties: CSS Property

• border-top-color, border-right-color, border-bottom-color, border-left-color:
The border color properties specify the color of the border area. The values of the border color properties belong to the <color> CSS data type.
border-top-color, border-right-color, border-bottom-color, border-left-color:
Value: <color> | transparent | inherit
Initial: the value of the color property
Applies to: all elements
Inherited: no
Percentages: n/a
Media: visual
Computed Value: as specified, when taken from the color property, the computed value of "color"
Style Group: box
Deprecated: no
Example: body {
   border-top-color: #ff0000; /*hex red*/
   border-right-color: #f00; /*shorthand hex*/
   border-bottom-color: red; /*named color*/
   border-left-color: rgb(255, 0, 0); /*RGB triplet-256 scale*/
}


• Border Color Shorthand Property: CSS Property
The border-color shorthand property sets the color for all four sides (border-top-color, border-right-color, border-bottom-color, border-left-color). Otherwise, the shorthand property behaves like the individual properties. The property definition is also like the individual properties with this one exception:
Value: [ <color> | transparent ]{1,4} | inherit
Example:   h4 { border-color: blue; } /*applies color to all edges*/


• Border Style Properties: CSS Property

• border-top-style, border-right-style, border-bottom-style, border-left-style:
The border style properties specify the style of the border area. The values of the border style properties belong to the <border-style> CSS property value group.
border-top-style, border-right-style, border-bottom-style, border-left-style:
Value: <border-style> | inherit
Initial: none
Applies to: all elements
Inherited: no
Percentages: n/a
Media: visual
Computed Value: as specified
Style Group: box
Deprecated: no
Example: body {
   border-top-style: double;
   border-right-style: none;
   border-bottom-style: double;
   border-left-style: none;
}


• Border Style Shorthand Property: CSS Property
The border-style shorthand property sets the style for all four sides (border-top-style, border-right-style, border-bottom-style, border-left-style). Otherwise, the shorthand property behaves like the individual properties. The property definition is also like the individual properties with this one exception:
Value: [ <border-style> | transparent ]{1,4} | inherit
Example:   h4 { border-style: groove; } /*applies style to all edges*/


• Border Width Properties: CSS Property

• border-top-width, border-right-width, border-bottom-width, border-left-width:
The border width properties specify the width of the border area. The values of the border width properties belong to the <border-width> CSS property value group.
border-top-width, border-right-width, border-bottom-width, border-left-width:
Value: <border-width> | inherit
Initial: medium
Applies to: all elements
Inherited: no
Percentages: n/a
Media: visual
Computed Value: absolute length; "0" if the border style is "none" or "hidden"
Style Group: box
Deprecated: no
Example: body {
   border-top-width: 6cm;
   border-right-width: 6cm;
   border-bottom-width: 6cm;
   border-left-width: 6cm;
}


• Border Width Shorthand Property: CSS Property
The border-width shorthand property sets the width for all four sides (border-top-width, border-right-width, border-bottom-width, border-left-width). Otherwise, the shorthand property behaves like the individual properties. The property definition is also like the individual properties with this one exception:
Value: <border-width>{1,4} | inherit
Example:   h4 { border-width: 3cm; } /*applies width to all edges*/


• Boundary: JavaScript RegExp
Patterns that need to match to a word only, can be built using word boundary tokens called boundaries. These tokens handle problems where the target word is the first and/or last word of a sentence. A "\b" token at the beginning of a pattern will anchor the pattern to a "\w" character. Also implied is the fact that a "\W" character preceded the anchor character (remember that "\b" anchors on a word boundary). The same logic applies when "\b" appears at the end of a pattern (it marks the end of the word and a "\W" character or end of line must follow).

• Box Model: CSS Property
The box model is a concept that aids user agents to render web pages consistently and predictably is support of the idea of document flow. Everything that is on a web page that is visible creates a box of a certain type. There are two basic box types. The block-level box flows onto the page in a vertical stacking manner. The inline-level box flows one after the other in a horizontal manner. The box model conforms to a preset structure. The structure consists of three boxes (margins, borders and padding) of varying dimensions where the larger box will act as a container for the smaller boxes. In the center of the box structure in the content of a given element. There is a collection of properties that support the box model and predominately define the space around the box containers.

• Box Style Group: CSS Property
The box style group is one of eleven property style groups that help define the total CSS property set. The box properties for this group apply directly to the box model. With the box model, the box encomposes (inner to outer) the content area, the padding area, the border area and the margin area. The box properties that comprise this group are:

• Backreference: JavaScript RegExp
The JS regular expression feature allows you to use values that were previously matched. These values are called backreferences. Groups within a pattern are given a reference numbers (but only for each group that had a successful match). The same pattern that contains the grouping sub patterns may also contain backreferences. The backreferences are indicated with the meta character "\" (a forward slash). This reference is then followed by a number that indicates the set of parentheses (or group) that captured the value.

• Bracket Operator: JavaScript Operator
The primary purpose of the bracket operator ( symbol: [ ] ) in JavaScript is to allow access to array elements. The element number ( index ) will exist inside the brackets and the associated array is the left of the brackets. The bracket operator can also give access to properties of an object. In this event, the second operand should be an expression that evaulates to a string. The string should be the name of a property of the referenced object ( 1st operand ).
The attributes of this operator are:

• break Statement: JavaScript Term
The break statement instructs the interpreter to exit a loop immediately. The entire looping control structure is broken with no additional iteration and program execution will resume at the next sequential statement. The break statement can only be used inside a repetition control structure (while, do/while, for, for/in) as well as the switch statement. The syntax of the continue statement includes the optional label identifier.

• Browser Object Model: BOM
The Browser Object Model is a common set of objects related to client operating environment, that is, the browser. The BOM objects are not part of the ECMA-262 specification. The BOM is not an industry standard and incompatibilities among browsers do exists. The BOM objects such as the window, navigator, history and screen are present in almost all browser implementations.

• Built-in Function: JavaScript Function
The methods of the Global object are sometimes referred to as built-in functions. These methods have global scope and stand alone reference names (they do not require a class qualifier and the dot operator for access).

• Built-in Object: JavaScript Object
A built-in object is a subset of the JS Native Objects. Built-in objects must be present at the start of the execution of an ECMAScript program. This differs from Native objects, where objects may be constructed during the course of execution. The two JS built-in objects are the Math object and the Global object. These two objects do not behave like a class as do the other Native objects. For example, built-in objects do not have class constructors.















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