WEB Developer's Glossary



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• Absolute Reference: Web
You can write a URI in one of two methods: absolute or relative. An absolute reference is a direct and complete path to a Web location. This path can be either an external reference or an internal reference. The base address (specified in the BASE element for HTML) has no affect on an absolute reference.

• Absolute Value CSS Property Values
The computed value is an intermediate value that the UA will arrive at in a four step process during the property value assignment task. The four step value assignment process is:
A computed value is resolved from the specified value. Arriving at an computed value may or may not require a computation. A specified value that is already an absolute value will not require a computation. However, relative values always require a computation.

• Abstraction: JavaScript OOD
Abstraction is one of the common OOD principles. Abstraction refers to the act of representing essential features without including the background details. With JS, the mechanism to allow abstraction is the class. The clients of a class will interface with the class without knowing the class internal details other than it's implementation. The other common OOD principles: encapsulation, Inheritance, aggregation and polymorphism.

• Access Operator Group: JavaScript Operator
The access operators ( the dot operator and the bracket operator ) provide access to objects and arrays. The parentheses operator provides access to a function by invoking the function. The new operator provides access to a special type of function called a constructor. The access operators have the highest precedence of all the JS operators.

• Access Specifier: JavaScript OOD
With most formal OOP languages, access specifiers determine who can gain access to a class member. JavaScript does not recognize formal access specifiers. In fact, all properties and methods in JavaScript have public scope by default. However, public, private, protected and static are reserved words for future ECMA-262 extensions.

• Accessor Method: JavaScript OOD
An accessor method does not alter data. These accessor methods are suited and often included in the prototype object. The members of a given prototype object are shared by all object instances of the relate class that have inherited from the prototype. Therefore, these members must remain consistent for all object instances of that class type. Be aware that the members of the prototype object can be altered; it is up to the programmer to assure they remain unaltered.

• Actual Parameter: JavaScript OOD
This topic is being addressed relative to a OOD focus. However, the topic applies to FSD also. The invoking statement will contain the actual parameters that will be passed to the method being called. The actual parameters should match (same signature) the formal parameters of the method definition. Formal parameters refer to the method heading of a method definition. Because JavaScript is weakly typed, the datatypes of the actual parameters will not be checked with the formal parameter in the method heading definition. Infact, JavaScript does not check that you have passed the correct number of parameters. If the actual parameters contain more parameters than the method's formal parameter set, then JavaScript will ignore the extra parameters. If the actual parameters contain less parameters than the method's formal parameter set, then JavaScript will assign the undefined value to the extra formal parameters.

To apply the above description to functions, replace "method" with "function" and remember the invoking statement for functions is the function call statement.

• Actual Value CSS Property Values
The actual value is the final value resolved during the property value assignment process and serves as the actual value the UA uses for rendering a property value. The actual value is resolved from the used value in the final step of a four step process. The four step value assignment process is:
  1. resolve the specified value,
  2. resolve the computed value from the specified value,
  3. resolve the used value from the computed value,
  4. resolve the actual value from the used value.

A used value is in principle the value used for rendering, but a user agent may not be able to make use of the value in a given environment. For example, a user agent may only be able to render borders with integer pixel widths and may therefore have to approximate the computed width, or the user agent may be forced to use only black and white shades instead of full colour. The actual value is the used value after any approximations have been applied.

• Addition Operator: JavaScript Operator
The addition operator ( symbol: + ) can perform three operations. If both operands are numbers, a simple arithmetic addition is the result. If both operands are a string, the second string is concatenated to the first. And lastly, when one operand is a string but the other is a number, the operator will convert the number to a string and then perform the concatenation. Special rules apply to NaN numbers and Infinity numbers.
The attributes of this operator are:

• Additive Operator Group: JavaScript Operator
The additive operator group is a ECMAScript term that includes both the addition operator and the subtraction operator. The additive operator group along with the multiplicative operator group make up the simple arithmetic operations of JS.

• after Selector: CSS Selector
The pseudo-element after selector lets you place generated content after 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.

• Aggregation: JavaScript OOD
Aggregation is one of the common OOD principles. Aggregation is the ability to store an object inside another object. This is the classic "has-a" relationship (every person "has-a" a birth date). Aggregation is a weaker form of composition. The other common OOD principles: encapsulation, Inheritance, abstraction and polymorphism.

• Alternation: JavaScript RegExp
Alternation will choose one pattern from a list of of patterns. The meta character for alternation is the vertical bar (pipe symbol). The alternation operation works the same as the bitwise OR operator.

• Ancestor: CSS 2.1 Specification
An element A is called an ancestor of an element B, if and only if B is a descendant of A.

• Anchor: JavaScript RegExp
Anchors in complex regular expression patterns are used to position regular expression search to a particular area of a target search string. A common anchor that positions a pattern at the beginning of a search string is the meta character "^" (caret). Likewise, the "$" will position a pattern at the end of a search string. Other types of anchors are boundary, assertion and multiline.

• Any Operand: JavaScript Operator
The any operand is an operand type of a JS operator that can take any and all other operand types.

• Applies to, CSS Property Definition: CSS Property
This part of the property definition lists the elements to which the property applies. All elements are considered to have all properties, but some properties have no rendering effect on some types of elements. For example, the "clear" property only affects block-level elements.

• Arguments Object: JavaScript Function
The Arguments Object is a temporary object designed to aid with function processing. This object will appear when a function is invoked and disappear when same function finishes. The Arguments Object contains properties that behave like array elements. The elements of the Argument Object contain the values of the actual parameters that were passed to the function when invoked. The Arguments Object and the Call Object are linked by the arguments property of the call object. The arguments property of the Call Object acts as a pointer to the Arguments Object.

• Argument Operand: JavaScript Function
A function call operator (   ) does not have a fixed number of operands. On the left of the operator is the named function ( function operand ). The function name is followed by the left parenthesis and any number of argument operands followed by the right parenthesis. The (   ) operator evaluates each operand and then invokes the function passing it the values as arguments. Functions that require multiple arguments have there arguments separated by commas.

• Arguments Property: JavaScript Function
The arguments property is a property of the Call Object. This property is a pointer to the array-like structure contained in the Arguments Object. This array-like structure is itself a set of properties that correspond to the actual parameters passed to the function when the function was invoked.

• Arithmetic Operators: JavaScript Operator
The arithmetic operators includes both the additive and multiplicative operator groups.

• Array: JavaScript Array
An array is a data structure consisting of related data items. With JS, the data items (or elements) are related only by there proximity (belong to the same data structure). Otherwise, any element of any array can represent any data type. Each individual array element has a position number (or index). The index is used to access individual elements. Array indexes begin at zero. Therefore, as an example, the 3rd element of an array has an index of two. JS supports arrays with the Array class. Array data structures can be built with the Array class constructor. JS also allows array data structures to be build with an Array literal format.

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

• Array Element: JavaScript Array
An array is a set of data values. Each member of the array's set of values is often referred to as an element. The individual elements of an array are unnamed, however, each element is assigned an integer. This integer is called the index and is used to access the element's data. The Array.length property value is equivalent to the total number of elements that make up the array. The term index and element are not synonymous. The index is the programmatical way to reference an element. The term "element" is a semantical aid for referencing the members of an array.

• Array Index: JavaScript Array
The individual elements of an array are unnamed. An array stores a numbered value for each element. The number assigned to each element is the index and it is used to reference the element's value. The first element of an array has an index of zero. The index of the last element of an array is: (Array.length - 1). The index must be an integer that is greater than or equal to zero. JavaScript will have problems when the index is a floating point number, a negative number or a number that exceeds the maximum (232-1).

• Array Initialize: JavaScript Expression
The ECMAScript term array initialize describes the act of initializing an array. We find this term is section 11.1.4 under the topic of "Primary Expressions". The ECMAScript description is as follows. An array initialize is an expression describing the initialization of an Array object, written in the form of a literal. It is a list of zero or more expressions, each of which represent an array element, enclosed in square brackets. The Array literal and the bracket operator are covered at the indicated links.

• Array Literal: JavaScript Array
The Array literal is enclosed in a matching set of square brackets, (bracket operator). Inside the brackets, is a set of data tokens that are separated by commas where each data token represents an element of the target array. The data token can be of any data type, both primitive types and reference types. Furthermore, any given Array literal can contain data tokens of differing data types. JS supports multidimensional arrays simply by accepting an Array data type as a data option for any given data token.

• Array Object: JavaScript Object
The Array object is a instance of the Array class type. An Array object can be declared and initialized by either the Array class constructor or by an Array literal statement. See our link for class for the distinction between the terms "class" and "object".

• Array Operand: JavaScript Array
The bracket operator, [ ], gives access to array elements. The bracket operator takes two operands. The operand to the left of the bracket operator is the name of the array and in this role, it is called the array operand. The second operand ( goes between the brackets ) should be an expression that evaluates to an integer. The second operand represents the index of the element in the array to which access is being granted.

• Array Type: JavaScript Data Type
The Array type is a data type that is associated with the Array class. The Array type belongs to the reference type group of data types. The reference type group also includes the Function type and the Object type. The reference type group differ from the primitive data type group in many ways. There representive data structure is more complex, memory management is more complex, memory access is slower and memory access is more complex. The data type dictates the nature of the data. Array data is comprised of elements, each capable of holding data representive of any of the other reference types or primitive types. Each element is separated by a comma. All elements of an array are enclosed in square brackets (array initilizer). The same square brackets (bracket operator) will aid in giving access to the individual elements. Each element is assigned a number called an index. The index inside the square brackets along with the array operand provide access to the element of the array.

• ASCII Character Set: Web
The ASCII (American Standard Code For Information Interchange) character set is a subset of many other more recent and universal character sets. The ASCII character set defines the first 128 characters of the Unicode character set. The ASCII character set is the grand daddy of American character sets. It's cousin is the extended ASCII or more commonly called the ISO Latin-1 character set. Extended ASCII takes up a whole byte or 256 codes. Where as ASCII takes up a half of the available codes in a byte, that is 128 codes.

• Assertion: JavaScript RegExp
An assertion in a pattern states that a match is required but do not include the characters in the match. It is a match with zero width. For example, a regular expression with an assertion used with the match( ) method, would require that the target string match the assertion however, the method would not return the assertion portion of the match in the resulting array.

• Assignment Operator Group: JavaScript Operator
The assignment operator group are operators that are used to assign a value to a variable. The assignment operator expects its lefthand operand to be a lvalue (a variable, an element, or a property). The righthand operand can be a value of any type. The value on the right is assigned to the lvalue on the left. This group of operators consists of the simple assignment operator and compound assignment operators.

• Assignment Statement: JavaScript Expression Statement
The assignment statement is a statement that contains an assignment operator. The assignment statement is an expression statement with the side effect being the left-hand-side operand's value being altered.

• Assignment With Operation Operator Group: JavaScript Operator
See compound assignment operator.

• Associative Array: JavaScript Array
An associative array is an unordered collection of key-value pairs. Rather than access an array element with an index, elements in an associtive array are accessed using a string known as a key. Each key of the array must be unique.

• Associativity: JavaScript Operator
Associativity in this definition is of and pertaining to JavaScript operators. The associativity of an operator specifies the order in which operations are performed in an expression where two or more operators are of the same precedence. Where an expression has only one operator or all operators are of a different precedence, then associativity does not come into play. When an expression has two or more operators with the same precedence, then the operation will procede either right-to-left or left-to-right depending on the associativity of the operators.

• Attribute: CSS 2.1 Specification
The attribute is a value associated with an element, consisting of a name, and an associated (textual) value.

• Attribute Selectors: CSS Selector
CSS allows selectors to be specified in rules where matching is based on elements that have a given attribute defined in the source document. These types of selectors are called attribute selectors. The simplest attribute selector requires that the attribute only be present for the defining element. For the simple attribute selector, the value of the attribute is not part of the match. The remaining attribute selectors (three) depend on a value along with the associated attribute and matching is performed on both attribute and it's value. See selector patterns for formats. Here are the links to the four types of attribute selectors:

• Attribute (Simple) Selector: CSS Selector
The simplest attribute selector requires that the attribute only be present for the defining element. For the simple attribute selector, the value of the attribute is not part of the match. See selector patterns for formats.

• Attribute Value Selector: CSS Selector
The attribute value selector depend on a value along with the associated attribute and matching is performed on both attribute and it's value. See selector patterns for formats.

• Attribute Space-Separated List Selector: CSS Selector
The space-separated list attribute selector depends on a value along with the associated attribute and matching is performed on both attribute and it's value. However, the value can be part of a list. This particular list must separate multiple values with spaces. The target attributes that reflect these types of space-separated list value are those that conform to data types that take string-like data (linktypes, text, script, etc.) See selector patterns for formats.

• Attribute Hyphen-Separated List Selector: CSS Selector
The hyphen-separated list attribute selector depends on a value along with the associated attribute and matching is performed on both attribute and it's value. However, the value can be part of a list. This particular list must separate multiple values with a hyphen. Of all the HTML attributes, there is only one attribute that can contain a hyphenated list. This attribute is the "lang" attribute. See selector patterns for formats.

• Author: CSS 2.1 Specification
An author is a person who writes documents and associated style sheets. An authoring tool is a User Agent that generates style sheets.

• Automatic Numbering: CSS Selector
The automatic numbering term refers to counters in conjunction with the content property that can be inserted into markup under the control of CSS. That is, the content property will render counters in conjunction with the counter-increment and counter-reset properties. These counters represent generated content under CSS control that is not part of the document language.















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