Platform Support
IE | Mozilla | Netscape | Opera | Safari | 3.0+ | 1.0+ | 3.0+ | 7.0+ | 1.0+ |
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Constructors
Constructor | Action | IE | Mozilla | Netscape | Opera | Safari | |||||
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Boolean Constructor(Boolean value) : Boolean
Creates a new instance of a Boolean object.
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Show Details | 3.0+ | 1.0+ | 3.0+ | 7.0+ | 1.0+ | |||||
Boolean(Boolean value) : BooleanCreates a new instance of a Boolean object. Parameters
Returns
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Properties
Property | Action | IE | Mozilla | Netscape | Opera | Safari |
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constructor
: Object
Specifies the function that creates the Boolean prototype.
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Show Details | 4.0+ | 1.0+ | 3.0+ | 7.0+ | 1.0+ |
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prototype
: Object
Represents the Boolean prototype object.
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Show Details | 4.0+ | 1.0+ | 3.0+ | 7.0+ | 1.0+ |
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Functions
Method | Action | IE | Mozilla | Netscape | Opera | Safari | ||
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toSource() : String
Returns a string representing the source code of a Boolean object.
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Show Details | 4.0+ | 1.0+ | 4.0+ | no | no | ||
Returns
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toString() : String
Returns a string representing the specified Boolean
object.
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Show Details | 4.0+ | 1.0+ | 3.0+ | 7.0+ | 1.0+ | ||
Returns
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valueOf() : Boolean
Returns the primitive value of a Boolean object.
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Show Details | 4.0+ | 1.0+ | 3.0+ | 7.0+ | 1.0+ | ||
Returns
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Creating Boolean
objects with an initial
value of false
bNoParam = new Boolean(); bZero = new Boolean(0); bNull = new Boolean(null); bEmptyString = new Boolean(""); bfalse = new Boolean(false);
Creating Boolean
objects with an initial
value of true
btrue = new Boolean(true); btrueString = new Boolean("true"); bfalseString = new Boolean("false"); bSuLin = new Boolean("Su Lin");
Remarks
Do not confuse the primitive Boolean values true and false with the true and false values of the Boolean object.
Any object whose value is not undefined
or null
, including a Boolean object whose
value is false, evaluates to true when passed to a
conditional statement. For example, the condition in the
following if statement evaluates to true:
x = new Boolean(false); if (x) //the condition is true
This behavior does not apply to Boolean primitives.
For example, the condition in the following if statement
evaluates to false
:
x = false; if (x) //the condition is false
Do not use a Boolean
object to convert a
non-boolean value to a boolean value. Instead, use
Boolean as a function to perform this task:
x = Boolean(expression); //preferred x = new Boolean(expression); //don't use
If you specify any object, including a Boolean object whose value is false, as the initial value of a Boolean object, the new Boolean object has a value of true.
myFalse = new Boolean(false); // initial value of false g = new Boolean(myFalse); //initial value of true myString = new String("Hello"); // string object s = new Boolean(myString); //initial value of true
Do not use a Boolean object in place of a Boolean primitive.
References
Availability
JavaScript 1.1|JScript 2.0|ECMAScript v1