Boolean : Object

constructor primitive

A true or false value.

Boolean(value : Object) : Boolean

Coerces value into a boolean value. You can also use !!value to do the coercion. Note 'false' coerces to true since it is a non-empty string. Use value === 'true' to convert a string to a Boolean.

Example:

console.log(Boolean(''));
console.log(Boolean('0'));
console.log(Boolean(0));
console.log(Boolean(1));
console.log(Boolean([]));
console.log(Boolean(undefined));
console.log(!!undefined);
console.log();

var stringToBoolean = function(value) {
  return value === 'true';
};
console.log(Boolean('false'));
console.log(stringToBoolean('false'));

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Constructors

new Boolean(value : Object) : Object

Creates a box for a boolean value.

Example:

var literal = true;
var boxed = new Boolean(true);

console.log(literal === true);
console.log(boxed === true);
console.log(boxed.valueOf() === true);
console.log();

// Literals cannot hold other properties but boxes can
literal.foo = 'bar';
boxed.foo = 'bar';
console.log(literal.foo);
console.log(boxed.foo);

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Instance Methods

toString() : String

Returns a string representation of this.

Example:

console.log(true.toString());
console.log(false.toString());

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Results:

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