Avoid self = this by using arrow functions ES6

In a JavaScript class, I have a function that calls a callback using a constructor's own variable. To not copy the entire class I will write an example:

class Foo {
    constructor(bar) {
        this.bar = bar;
    }

    async_print() {
        setTimeout( function() {
            console.log(this.bar);
        }, 1000);
    }
}

This gives an error because this refers to the context of the function and not to the Foo object, so I tend to solve it by using a variable self that refers to this when still It's what I want it to be. For example:

class Foo {
    constructor(bar) {
        this.bar = bar;
    }

    async_print() {
        const self = this;

        setTimeout( function() {
            console.log(self.bar);
        }, 1000);
    }
}

However, I am left with the feeling that the use of a variable self is a fix that should be avoided. I know there is a solution through the binding, but I have also seen that in ES6 you can call an arrow function.

In the Mozilla developer documentation, it is explained by using this example :

function Persona(){
  this.edad = 0;

  setInterval(() => {
    this.edad++; // |this| apunta al objeto Persona
  }, 1000);
}

However, that only works for me if I have to use a function or act with a variable, but it does not help me to obtain it directly. That is, I can not return such value to use it for example in console.log . We are talking about a value that I use many times, so I do not see viable doing an arrow function every time I need to interact with it.

What am I missing? How can I get that value within the callback?

Thank you very much