JSFiddle - React, Tailwind, and code Playground

HTML

<span id="output"></span>

JavaScript

var makePerson = function(favoriteColor, name, age) {
  if (arguments.length < 3) {
    this.name = arguments[0];
    this.age = arguments[1];
    favoriteColor = "green";
  }

  return {
    name: this.name,
    age: this.age,
    favoriteColor: favoriteColor
  };
};

var person = makePerson("Joe", 18);

$('#output').text(JSON.stringify(person));