On the basic knowledge of constructor_ in JavaScript

constructor, constructors, we are not unfamiliar with this name,constructor always point to the constructor that created the current object.

One thing to note here is that each function has a prototype attribute, and this prototype constructor points to the function, which is unexpected when we modify the prototype of this function. Such as

function Person (name,age) {
  this.name = name;
  This.age = age;
}

Person.prototype.getAge = function () {return
  this.age;
}
Person.prototype.getName = function () {return
  this.name;
}

var p = new Person ("Nicholas",);
Console.log (P.constructor); Person (name, age)
Console.log (P.getage ());//18
Console.log (P.getname ());//nicholas

But if this is the case:

function Person (name,age) {
  this.name = name;
  This.age = age;
}

Person.prototype = {
  getname:function () {return
    this.name;
  },
  getage:function () {
    return This.age
  }
}

var p = new Person ("Nicholas",);
Console.log (P.constructor); Object ()
Console.log (P.getage ());//18
Console.log (P.getname ());//nicholas

The result constructor changed.

The reason is that prototype itself is also an object, and the code above is equivalent to

Person.prototype = new Object ({
  getname:function () {return
    this.name;
  },
  getage:function () { return
    this.age;
  }
});

Because constructor always points to the constructor that creates the current object, it is not difficult to understand that the above code p.constructor Output is object.

What about the constructor that changed the prototype and wanted it to point to person? Simply, assign a value directly to the Person.prototype.constructor:

Person.prototype = {
  Constructor:person,
  getname:function () {return
    this.name;
  },
  getage: function () {return
    this.age;
  }
}

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