Why is this pattern not correct?

Question

JavaScript

var obj = {};
  
var Singleton = function(){
 if(!obj) { 
var obj = {};
}
 
  return obj;
  
  }
  
var o  = new Singleton();
var o1 = new Singleton();

o.prop = 's'; 
console.log(o === o1);  //false
console.log(o1.prop); //undefined

Answer 1

Because the objects ( oand o1) are different, each has its own obj.
The very idea of ​​a singleton is that it is one object (type) for the entire program.

function Singleton () {
    if (Singleton._instance) return Singleton._instance;
    Singleton._instance = this;
};

var o = new Singleton();
var o1 = new Singleton();
console.log(o === o1); // true

o.prop = 's';
console.log(o1.prop); // s

Answer 2

<sarcasm>Because a singleton is an antipattern.</sarcasm>
In general, read this:
- constructor functions
- hoisting

Answer 3

Singleton always returns only 1 object and does not create a new one.
You have a new object generated with each new