Javascript [Electronic resources] : The Definitive Guide (4th Edition) نسخه متنی

Availability

JavaScript 1.1; JScript 2.0; ECMAScript
v1

Inherits from/Overrides

Inherits from Object

Constructor

new Boolean(value) //Constructor function
Boolean(value) // Conversion function

Arguments

value

The value to be held by the Boolean object or to be converted to a
boolean value.

Returns

When invoked as a constructor with the new
operator, Boolean( ) converts its argument to a
boolean value and returns a Boolean object that contains that value.
When invoked as a function, without the new
operator, Boolean( ) simply converts its argument
to a primitive boolean value and returns that value.

The values 0, NaN, null, the empty string
", and the undefined value are
all converted to false. All other primitive
values, except false (but including the string
"false"), and all objects and arrays are converted to
true.

Methods

toString( )

Returns true or false,
depending on the boolean value represented by the Boolean object.

valueOf( )

Returns the primitive boolean value contained in the Boolean object.

Description

Boolean values are a fundamental data
type in JavaScript. The Boolean object is an object wrapper around
the boolean value. This Boolean object type exists primarily to
provide a toString( ) method to convert boolean
values to strings. When the toString( ) method is
invoked to convert a boolean value to a
string (and it is often invoked
implicitly by JavaScript) JavaScript internally converts the boolean
value to a transient Boolean object, on which the method can be
invoked.

See Also

Object