Effect of "new" in JavaScript

Question

I have written some code I found in a video, and it looks something like this:

var clientX = clientX || {} ; 
clientX.MyClass = function(initialValue){
 var var1 = initialValue;
 var publicMembers = {
 get_var1 : function(){
 return var1; 
 }
 };
 return publicMembers;
}
var result = new clientX.MyClass("val1");
alert(result.get_var1());
clientX.instance = new clientX.MyClass("val2");
alert(clientX.instance.get_var1());
clientX.instance2= new clientX.MyClass("val3");
alert(clientX.instance2.get_var1());

The thing is, after deleting the "new" keyword when I use : var result = new clientX.MyClass("val1"); Nothing is changed, so why the author chose to use it? What's the effect?

• Henrik Andersson: possible duplicate of What is the 'new' keyword in JavaScript?

Answer 1

The MyClass function makes no use of this and has an explicit return value, so the use of new has no practical effect whatsoever.

Answer 2

the new keyword is used as a piece of pseudoclassical instantiation, wherein a constructor object has properties attached to the keyword "this" but no return value is ever written.

var Car = function(){
 this.color = 'blue';
 this.make = 'toyota';
 this.model = 'camry';
}

now, writing var x = new Car() will add the following lines to the interpretation:

var Car = function(){
 var this = {}; //added by new
 this.color = 'blue';
 this.make = 'toyota';
 this.model = 'camry';
 return this; //added by new
}