OBJECT:
Boolean
new
Boolean(value)
The Boolean object is an object wrapper for a Boolean value
and is constructed with the above Boolean constructor. If there is no
initial value or if it is 0, -0, null, false, NaN,
undefined, or the empty string (""), the initial value is false.
Otherwise, even with the string "false", it is true. So, all the following
objects have an initial value of false:
x = new Boolean()
x = new Boolean(0)
x = new Boolean(-0)
x = new Boolean(null)
x = new Boolean(false)
x = new Boolean(NaN)
x = new Boolean(undefined)
x = new Boolean("")
...whereas in the following examples the Boolean object 'x' has an
initial value of true:
myBool = new Boolean(false)
x = new Boolean(myBool)
x = new Boolean("false")
Any Boolean object that is passed to a conditional statement
(except those with an initial value of null or undefined)
evaluates to true. So, for instance, the conditional statement in the
following code evaluates to true.
Code:
x = new Boolean(false)
if(x)
However, this does not apply to Boolean primitives, and the conditional
statement in the following code evaluates to false.
Code:
x = false
if(x)
NOTE:
In JavaScript 1.3 and later versions, don't use a Boolean object
instead of a Boolean primitive, nor should you use a Boolean
object to convert a non-Boolean value to a Boolean one. To do so use
Boolean as a function. For example, the following converts the
expression 'a+b' to a Boolean value:
Code:
x = Boolean(a+b)
PROPERTIES
constructor property
This property specifies the function that created the object's prototype.
See also the Object.constructor
property.
Syntax: object.constructor
prototype property
This property represents the prototype for this object and allows you
to add methods and properties of your own. See also the Function.prototype
property.
Syntax: object.prototype
METHODS
toSource method
This method, which is usually called internally by JavaScript, returns
a string representing the source code of the object. It overrides the
Object.toSource method.
Syntax: object.toSource()
toString method
This method converts a Boolean object to a string representing
its value: i.e. either "true" or "false", and is called by JavaScript
automatically whenever a Boolean object is used in a situation
requiring a string. This method overrides the Object.toString
method.
Syntax: object.toString()
valueOf method
This method, which is usually called internally by JavaScript, returns
a primitive value (either "true" or "false") for the Boolean
object. It overrides the Object.valueOf
method.
Syntax: object.valueOf()
NOTE:
The Boolean object also inherits the watch
and unwatch methods from the
Object object.
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