DevGuru JavaScript OBJECT: Boolean



			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.