javascript - What EXACTLY is new doing?

Question

This is going to be a tricky question. Having a constructor:

var Constructor = new function(){
this.a = 'a';
this.b = 'b';
}

we can create an object:

var obj = new Constructor();

this in Constructor refers to window but when calling new Constructor() some magic is being done: now this is finding out the scope of a function it is in (how exactly is it working?) and assigning only that scope to obj returns it. So basically it is doing something like:

var Constructor = new function(){
var this = {some object having variables needed for every object (like __proto__)}    
this.a = 'a';
this.b = 'b';
return this;
}

Can anyone tell me how it is this mechanism of creation of new object in JS is working in low level? What exactly is being done underneath when calling new?

Answer 1

“new SomeFunction()”正在创建一个新对象，并以该对象为“this”调用 SomeFunction。

考虑一下：

function SomeFunction() {
    this.hello = "Hello, world";
}
var myObj = new SomeFunction();
myObj.hello; // "Hello, world"

var myObj2 = {};
SomeFunction.call(myObj2);
myObj2.hello; // "Hello, world"