Why do developers use "_" while using get and set in JavaScript?

Question

I know that using an underscore is just a convention to define private variables in JavaScript. But I came across a use case [while using a class] where use of _ seems mandatory to make the code work! My question is how _ is used under the hood by get and set.

The below code throws an error:

RangeError: Maximum call stack size exceeded

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

  get name() {
    return this.name;
  }

  set name(val) {
    this.name = val;
  }
}

let user = new User("Jhon");
console.log(user.name);

Now, if I use _ the code works!

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

  get name() {
    return this._name; // Added "_" here
  }

  set name(val) {
    this._name = val; // Added "_" here
  }
}

let user = new User("Jhon");
console.log(user.name);

Answer 1

Just look at this piece of code logically:

get name() {
    return this.name
}

You read object.name. To return a value, the get name() getter reads this.name, which, in turn, resolves to get name(). And now, welcome to the infinite loop.

Hence, you need a separate variable name (to store the actual content of name) than the getter's name. That would be a private variable, and it has become a convention to prepend an underscore in these cases.