JSFiddle - React, Tailwind, and code Playground

JavaScript

function Person(firstName){
	this.firstName = firstName;
}

Person.prototype.speak = function(){
	setTimeout(function(){
  alert('my name is: ' + this.firstName)
  }this, 10);
}

Person.prototype.speakArrowFunction = function(){
	setTimeout(() => {
  alert('my name is: ' + this.firstName)
  }, 10);
}

new Person('alex').speak()
new Person('alex').speakArrowFunction()