Summary

The Boolean object is an object wrapper for a boolean value.

Syntax

new Boolean(value)

Parameters

value

The initial value of the Boolean object.

Description

The value passed as the first parameter is converted to a boolean value, if necessary. If value is omitted or is 0, -0, null, false, NaN, undefined, or the empty string (""), the object has an initial value of false. All other values, including any object or the string "false", create an object with an initial value of true.

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) {
  // . . . this code is executed
}

This behavior does not apply to Boolean primitives. For example, the condition in the following if statement evaluates to false:

x = false;
if (x) {
  // . . . this code is not executed
}

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.

Properties

For properties available on Boolean instances, see Properties of Boolean instances.

prototype: Defines a property that is shared by all Boolean objects.

Methods

For methods available on Boolean instances, see Methods of Boolean instances.

The global Boolean object contains no methods of its own, however, it does inherit some methods through the prototype chain.

Boolean instances

All Boolean instances inherit from Boolean.prototype. As with all constructors, the prototype object dictates instances' inherited properties and methods.

Examples

var bNoParam = new Boolean();
var bZero = new Boolean(0);
var bNull = new Boolean(null);
var bEmptyString = new Boolean("");
var bfalse = new Boolean(false);

var btrue = new Boolean(true);
var btrueString = new Boolean("true");
var bfalseString = new Boolean("false");
var bSuLin = new Boolean("Su Lin");

Browser compatibility

See also

• Boolean.prototype
• Boolean data type