JSFiddle - React, Tailwind, and code Playground

JavaScript

"use strict";
var userOne = {
    firstName: 'anon',
    sayHi: function() {
        alert(this.firstName);
    }
};



var userTwo = {
    name: 'anon',
    sayHi: function() {
        alert(this.name);
    }
};

setTimeout(userOne.sayHi, 1000); // undefined
setTimeout(userTwo.sayHi, 1000);	// пусто