Instance Property

isUndefined

A Boolean value that indicates whether the instance corresponds to the JavaScript undefined value.

Declaration

var isUndefined: Bool { get }

Discussion

The JavaScript undefined value is used for variables that have not yet been assigned a value, for formal parameters in functions for which no actual parameter has been passed, and as the result of expressions or function calls that do not explicitly return a value. Note that undefined is not the same as null.

See Also

Determining the Type of a JavaScript Value

var isNull: Bool

A Boolean value that indicates whether the instance corresponds to the JavaScript null value.

var isBoolean: Bool

A Boolean value that indicates whether the instance is a JavaScript Boolean value.

var isNumber: Bool

A Boolean value that indicates whether the instance is a JavaScript numeric value.

var isString: Bool

A Boolean value that indicates whether the instance is a JavaScript String object.

var isObject: Bool

A Boolean value that indicates whether the instance is a JavaScript object.

var isArray: Bool

A Boolean value that indicates whether the instance is a JavaScript array value.

var isDate: Bool

A Boolean value that indicates whether the instance is a JavaScript Date object.