differences between Boolean answers in javascript

Question

why these two code has different answers:

code 1 answer is false code 2 answer is true

code 1

var x = Boolean (false);
if (x) 
{
      console.log (true);
}
else 
{
      console.log (false);
}
// answer is false

code2

var x = new Boolean (false);
if (x)
{
     console.log (true);
}
else 
{
     console.log (false);
}

//answer is true

Possible duplicate of [Why does !new Boolean(false) equals false in JavaScript?](http://stackoverflow.com/questions/8695341/why-does-new-booleanfalse-equals-false-in-javascript) — Michał Perłakowski, Jan 09 '16 at 09:00

yurzui · Answer 1 · 2016-01-09T09:13:22.740

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.

From https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Boolean

The global function Boolean() can be used for type casting when called without new, eg

var foo = Boolean(param); // equivalent to `var foo = !!param`

When called with new, a wrapper object will be created additionally, which means that you can assign arbitrary properties to the object:

var foo = new Boolean(param); // equivalent to `var foo = Object(Boolean(param));`
console.log(foo === true) // true, because object - true
foo.prop1 = 'test';

score 1 · Accepted Answer · answered Jan 09 '16 at 09:02

The first block omits the "new" keyword, x is assigned the value of Boolean(expr), which is a function that converts a non-boolean value to a boolean one.

The second block creates a Boolean object, the if conditional returns true because x is not undefined.

differences between Boolean answers in javascript

code 1

code2

2 Answers2