Adding a method to a class using .prototype

Question

I am attempting to define a class called "User"... then further along in the code I am trying to add a method to the class by writing to "prototype". I'm not sure if my terminology is correct here... though I would like to have the method "who_auto" available to all future instances of "User"...

Trying out this code in JSFiddle... is giving me the error message: "Uncaught TypeError: pp.who_auto is not a function"

Here's my code:

class User {
  constructor(name) {
    this.name = name;
    this.chatroom = null;
  }

  who() {
    return `I am ${this.name}`;
  }
}

User.prototype = {
  who_auto: function() {
    console.log(`
  Hello, I am ${this.name}
  `);
  }
}
const pp = new User('peter parker');
console.log(pp);
console.log(pp.who());

pp.who_auto();

Answer 1

You overwritten the prototype instead of adding a property to the prototype. Below codes works.

class User {
  constructor(name) {
    this.name = name;
    this.chatroom = null;
  }

  who() {
    return `I am ${this.name}`;
  }
}

User.prototype.who_auto = function() {
  console.log(`Hello, I am ${this.name}`);
}

const pp = new User('peter parker');
console.log(pp);
console.log(pp.who());

pp.who_auto();