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Microsoft® JScript Glossary |
Language Reference
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American Standard Code for Information Interchange (ASCII) 7-bit character set widely used to represent letters and symbols found on a standard U.S. keyboard. The ASCII character set is the same as the first 128 characters (0–127) in the ANSI character set.
A bit-by-bit comparison of identically positioned bits in two numeric expressions.
An expression that evaluates to either true or false. Non-Boolean expressions are converted to Boolean values, when necessary, according to the following rules:
- All objects are considered true.
- Strings are considered false if and only if they are empty.
- null and undefined are considered false.
- Numbers are considered false if and only if they are zero.
A number that represents a particular character in a set, such as the ASCII character set.
Text added to code by a programmer that explains how the code works. In JScript, a comment line generally starts with //. Use the /* and */ delimiters to create a multiline comment.
A character or symbol indicating a relationship between two or more values or expressions. These operators include less than (<), less than or equal to (<=), greater than (>), greater than or equal to (>=), not equal (!=), and equal (==).
A sequence of statements enclosed in braces ({}). Can be used to perform multiple tasks any time a single statement is expected.
A JScript function that has two special features:
Use constructors to initialize new objects.
- It is invoked by the new operator.
- It is passed the address of a newly created object through the this keyword.
A combination of keywords, operators, variables, and literals that yield a string, number, or object. An expression can perform a calculation, manipulate characters, call a function, or test data.
The set of information that corresponds to a given language and country. A locale affects the language of predefined programming terms and locale-specific settings. There are two contexts where locale information is important:
- The code locale affects the language of terms such as keywords and defines locale-specific settings such as the decimal and list separators, date formats, and character sorting order.
- The system locale affects the way locale-aware functionality behaves, for example, when you display numbers or convert strings to dates. You set the system locale using the Control Panel utilities provided by the operating system.
A value indicating that a variable contains no valid data. null is the result of:
- An explicit assignment of null to a variable.
- Any operation between expressions that contain null.
Any expression that can be evaluated as a number. Elements of the expression can include any combination of keywords, variables, literals, and operators that result in a number. In certain circumstances, strings are also converted to numbers if possible.
A named attribute of an object. Properties define object characteristics such as size, color, and screen location, or the state of an object, such as enabled or disabled.
An error that occurs when code is running. A run-time error results when a statement attempts an invalid operation.
Defines the visibility of a variable, procedure, or object. Variables declared in functions are visible only within the function and lose their value between calls.
A comparison of two sequences of characters. Unless specified in the function making the comparison, all string comparisons are binary. In English, binary comparisons are case-sensitive; text comparisons are not.
Any expression that evaluates to a sequence of continuguous characters. Elements of a string expression can include a function that returns a string, a string literal, a String object, or a string variable.
A special value given to variables after they are created and before a value has been assigned to them.
A location used for storing and manipulating values by name. As JScript is loosely typed, a single variable can hold different types of data over the course of a script.