JSFiddle - React, Tailwind, and code Playground

JavaScript

var myClass = function() {
  this.stuff = 1;
}
myClass.prototype.myFunc = function() {
  // Do Something..
  this.stuff += 5;
}

// Then create instances of your class with
var i = new myClass();

var j = new myClass();

console.log(i.stuff);
console.log(j.stuff);

j.myFunc();

console.log(i.stuff);
console.log(j.stuff);