Few observations with Boolean, NULL and NaN in JavaScript

Boolean is the one of primitive data type in the JavaScript. Below are the some observations while working with the Boolean.

// scenario one

var myBool = true;

alert(typeof myBool);//boolean

alert(myBool instanceof Boolean)// false

//scenario two

var myBool = new Boolean(false);

alert(myBool);

alert(myBool instanceof Boolean);//true

//numerics as Boolean

var myTruthValue = 0;

alert(Boolean(myTruthValue));//false

var myTruthValue = 1;

alert(Boolean(myTruthValue));//true

var myTruthValue = -1;

console.log(Boolean(myTruthValue));//true

when ever you are converting 0 to Boolean it yields false, other than 0 it may be a positive or negative it yields true;

var myTruthValue = 0;
alert(Boolean(myTruthValue));
alert(Boolean(myTruthValue) ==  false);// true


var myTruthValue = 1;
alert(Boolean(myTruthValue));
alert(Boolean(myTruthValue) ==  false);// false

//strings as Boolean

var myBool ="a";
alert(Boolean(myBool));//true

var myBool ="a";
alert(Boolean(myBool));//true

var myBool ="";
alert(Boolean(myBool));//false

alert(Boolean(myBool) == true);// true

Some observations with NULL
var myvar = null;
alert(typeof myvar)//object

//null is an Object?..... try with instanceof
alert(myvar instanceof Object);//false

var myval = null;
alert(myval == null);//true

Some observations with NaN

Nan means not a numeric value.we can check a given variable or value is numeric or not...for that we can use isNaN(value).. 

var myval = NaN;

alert(typeof myval);// Number

//one more surprise, NaN is Number?....

alert(isNaN(myval))//true

alert(isNaN(myval))//true

//NaN and numaric string literal

var myval = "-20";

alert(typeof myval);// string

alert(isNaN(myval))//false

myval = parseInt(myval);

alert(typeof myval);//number

alert(isNaN(myval))//false

//one more observation 

alert (NaN == NaN);//false 

var myvar = NaN;

alert (myvar == NaN);//false

i hope above observation will help you in some situations while coding... happy coding friends....

var myval = NaN;
alert(typeof myval);// Number

var myTruthValue = 1;
alert(Boolean(myTruthValue));//true

var myTruthValue = 1;
alert(Boolean(myTruthValue));//true