javascript - Prototypal Inheritance: Object.defineProperty (why to set writable to true)

Question

I was following along the MDN article on prototypes and inheritance and had a question about the old syntax (as opposed to the ES6 class syntax).

So let's look at the following:

function Person(first, last, age, gender, interests) {
  this.name = {
    first,
    last
  };
  this.age = age;
  this.gender = gender;
  this.interests = interests;
};

Person.prototype.sayWords = function() {
  console.log("blah blah");
}

function Teacher(first, last, age, gender, interests, subject) {
  Person.call(this, first, last, age, gender, interests);

  this.subject = subject;
}

Teacher.prototype = Object.create(Person.prototype); // To set up inheritance

// Fix constructor property to point to Teacher instead of generic Person
Object.defineProperty(Teacher.prototype, 'constructor', {
    value: Teacher,
    enumerable: false,
    writable: true 
});

Now, I understand the descriptor "writable" is used to allow/disallow assignment, but I'm not sure why the MDN article defaults to setting it to true whenever it uses this pattern to fix the constructor. Is that preferred over setting it to false? Are there a lot of situations where you think "I'd like to assign something else to this constructor property"?

Answer 1

等待大神答复