Top-Level Properties and Functions

These are core properties and functions, which are not associated with any lower-level object, although in the terminology used by ECMAScript and by Jscript, they are described as properties and methods of the global object.

Top-Level Properties

These were introduced in JavaScript 1.3 and Jscript 3.0, but in previous versions, Infinity and NaN existed as properties of the Number object.

Property	Introduced	Description
Infinity	JavaScript 1.3 Jscript 3.0	Returns infinity.
NaN	JavaScript 1.3 Jscript 3.0	Returns a value that is not a
undefined	JavaScript 1.3	Indicates that a value has not been assigned to a variable. Not supported by Internet Explorer.

Top-Level Functions

Function	Introduced	Description
decodeURI	JavaScript 1.5	Used to decode a URI encoded with encodeURI.
DecodeURIcomponent	JavaScript 1.5	Used to decode a URI encoded with encodeURIComponent.
encodeURI	JavaScript 1.5	Used to compose a new version of a complete URI replacing each instance of certain characters. It is based ipo the UTF-8 encoding of the characters.
encodeURIComponent	JavaScript 1.5	Used to compose a new version of a complete URI by replacing each instance of the certain character with escape sequences. Representation is via the UTF encoding of the characters.
escape()	JavaScript 1.0 Jscript 1.0	Used to encode a string in the ISO Latin-1 character set, for example to add to a URL.
eval()	JavaScript 1.0 Jscript 1.0	Returns the result of the JavaScript code, which is passed in as a parameter.
isFinite()	JavaScript 1.3 Jscript 3.0	Indicates whether the argument is a finite number.
isNaN()	JavaScript 1.0 Jscript 1.0	Indicates if the argument is not a number. (Unix only), 1.1
Number()	JavaScript 1.2 Jscript 2.0	Converts an object to a number.
parseFloat()	JavaScript 1.0 Jscript 1.0	Parses a string and returns it as a floating-point number.
parseInt()	JavaScript 1.0 Jscript 1.0	Parses a string and returns it as an integer. An optional second parameter specifies the base of the number to be converted.
String()	JavaScript 1.2 Jscript 1.0	Converts an object to a string.
unescape()	JavaScript 1.0 Jscript 1.0	Returns the ASCII string for the specified hexadecimal encoding value.