WEB Developer's Glossary

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• Table Style Group: CSS Property
The table style group is one of eleven property style groups that help define the total CSS property set. The table style group contains the properties that represent how CSS assists in laying out a table. HTML tables are easy to relate to but XML tables can use any element name to represent table features (cells, rows, columns). Therefore, CSS has enhanced the display property with numerous table based values to help with XML tables. Using tables to layout page design is no longer recommended (use CSS positioning properties), however, using tables to present data that is logically related is appropriate. The complete list of properties that comprise the table style group are:

• Ternary Operator: JavaScript Operator
A ternary operator is a JS operator with three operands. The only JS ternary operator is the conditional operator.

• Text Style Group: CSS Property
The text style group is one of eleven property style groups that help define the total CSS property set. The text style group contains the properties that aid in styling text content. Many of the properties and their values were designed to replace HTML text presentation attributes that have been deprecated with HTML 4.01. The complete list of properties that comprise the text style group are:

• this Keyword: JavaScript Term
The this keyword is a reference. The object through which an instance method is invoked becomes the value of the this keyword. It is a special property of the method. When used in a contructor, the this keyword is a reference to the object being instantiated. Here, the new operator will pass the newly created object as the value of the this keyword.

• throw Statements: JavaScript Term
The throw statement is used when the programmer throws an exception. throw is a keyword in JS. The throw statement is used in conjunction with the try/catch/finally statement. The explicit throw statement designed by the programmer must reside in the try clause. The catch clause performs the recovery processing. The programmer supplies an expression with the throw statement that can be: This expression is what is tested in the catch clause to determine what error was thrown and what corrective action is required.

• Tiling: CSS & HTML
The term tiling pertains to background images that fill the alloted background space by repeating the image both down and to the right. With HTML, the image is specified with the BACKGROUND attribut of the BODY element. The user agent will facilitate tiling automatically. However, the BACKGROUND attribute has been deprecated in favor of the CSS background-image property. In addition, CSS provides the background-repeat property to control (override the automatic tiling) the user agent's tiling mechanism.

• Token: JavaScript Term
A token is the smallest lexical unit of a programming language (categorized block of text). Tokens must be contiguous characters. That is, a space would change the meaning possibly causing two tokens instead of one. The lexical analyser reads in a stream of characters and categorizes them into tokens. This is called "tokenizing". The tokens is JavaScript can be: keywords, literals, operators and identifiers.

• Top Level Code: JavaScript Term
JavaScript statements that are specified within the <script> tag set that in turn are specified within the <head>tag set are termed as being top level code. Top level code has special behavior. Variable declared at top level have global scope. Global variables are accessible from anywhere within a JS program. Variables declared within a function or from a <script> tag set that resides within the <body> tags will all have local scope.

• Tree Relationships, The Document Web
The Document Tree relationships are a set of different relationship possibilities that exist in the document tree and can link the different elements together. The most common tree relationships are briefly described here with a link to additional detail:
  • ancestor: An ancestor is an element that is connected to another element, either directly, or through any other element, but is above it in the document tree. All connecting steps must point downward.
  • descendant: A descendant is considered the opposite of the ancestor relationship. It refers to any element that is connected to any other element, directly, or through any other element, but is below it in the document tree. All connecting steps must point upward.
  • parent: The parent is the element that is directly connected to the element below it. In the document tree, every element must have one parent, and only one parent, apart from the root element, which has none.
  • child: A child is similar to but opposite of the parent relationship, except that a parent can have multiple children. A child is an element that is directly connected to an element above it.
  • sibling: Siblings are a group of two or more elements that share the same parent. These elements need not be of the same type, they merely have to be children of the same parent element.
  • root: every document has one and only one root element. All other elements descend from the root element. For HTML documents, the HTML opening tag is the root element.
The terms parent and child are specific applications of the terms ancestor and descendant. But there is a difference. When the separation is only one level, we hace a parent-child relationship. When separation is two or more levels, we have an ancestor-descendant relationship. Of course the parent-child relationship also qualifies as a ancestor-descendant relationship but not visa-versa.

• try/catch/finally Statements: JavaScript Term
The try/catch/finally statements are three separate statements that work together to capture and process exceptions. The try statement encloses a block of code in which an exceptional condition can occur, such as a runtime error or a throw statement. The catch clause provides the exception handling code. When a catch clause catches an exception, its identifier is bound to the exception. The finally statement is optional but when specified, will execute regardless of whether an exception occurred. The catch statement will execute only when an exception occurred that has the corresponding identifier.

• Type: Core ECMAScript
The ECMA-262 standard defines the term type as a set of data values. We interchange the use of the term data type with the term type. A variable in JavaScript can hold one of two types of values: primitive values and reference values.

• Type Conversion: JavaScript Data Type
Data types in JS are not always set in stone. A variable that has been declared and initialized will exhibit a JS data type via the weak typing method. This same variable can be reinitialized and retyped with a literal value representive of a type completely different from the orignial type. This is automatic type conversion. In addition, constructor functions of primitive types can be used as conversion functions. Simply use the function without the new operator and use an argument to the function that is out of normal context for the function. This is explicit type conversion. And finally, JS has provided special methods designed specifically to convert data types.

• Type Selector: CSS Selector
The type selector will match all instances of the element type in the document's document tree. XML allows the creation of new markup languages meaning that element name possibilities have no limits. When you are styling a document whose document language is HTML, then the element type can be one of 91 HTML elements.

• TypeError Subclass: JavaScript Class
The JS interpreter can throw an instance of the TypeError subclass when the value is not of the type required for the given context. The JavaScript programmer can also create TypeError instances with the TypeError class constructor for the purpose of capturing the run-time exceptions. The TypeError subclass inherits from the Error class that acts as a super class. The complete set of error subclasses are: EvalError, RangeError, ReferenceError, SyntaxError, TypeError, URIError.

• typeof Operator: JavaScript Operator
The unary typeof operator ( keyword: typeof ) returns data type. The operand to the typeof operator may be of any operand type. The primitive types all evaluate to like type except for null. Null will evaluate to "object". Reference types ( arrays, objects ) evaluate to "object" while a function evaluates to "function".
The attributes of this operator are:


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