javascript - Answer: When the instance object calls the constructor, what is the point of this in the constructor?

Question

This problem actually comes from when analyzing the jQuery source code, I saw that var ret = jQuery.merge(this.constructor(), elems );, where this.constructor() returns The empty instance object created by the init method. Therefore, I am confused about the direction of this.
The following is the test code:

function Person() {
    this.name = 'ddadaa';
    console.log(this);
}
var p1 = new Person();
p1.constructor();        //  Person {name: "ddadaa"}
var p2 = p1.constructor;
p2();                    //打印的是window

Why is it that when constructor() is called directly here, the pointer of this changes and a new object is automatically created? Does the internal implementation of the constructor() method have an impact on this?

Answer 1

This has nothing to do with the internal implementation of the constructor() method. It is actually a problem pointed to by this within the function.
When the function is called as a property of the object, this points to the object;
When the function is called directly, in non-strict mode, this points to window;
p1.constructor points to Person function, when calling p1.constructor();, Person is called as an attribute of p1, so this points to p1; when calling var p2 = p1.constructor;p2( );, it is actually equivalent to calling Person(); directly, so this points to window.