JSFiddle - React, Tailwind, and code Playground

JavaScript

function doIt2() {
  this.f = () => {
    console.log("f called ok");
    this.g();
  }
  this.g = () => {
    console.log("g called ok");
  }
}
class doIt {
    f() {
      console.log("f called");
      this.g();
    }
    g() {
      console.log("g called");
    }
}

var n = new doIt();
n.f();
var n2 = new doIt2();
n2.f();

setTimeout(n.f,1000);
setTimeout(n2.f,1000);