JSFiddle - React, Tailwind, and code Playground

JavaScript

function MyClass() {
  var defaults = {
    myArr: [],
    myProp: 'I\'m a default value'
  }
  if (typeof options === 'object') {
    _.extend(this, defaults, options);
  } else {
    _.extend(this, defaults);
  }
}

var myObj = new MyClass({
  foo: 'bar'
})
myObj.myArr.push('baz')
var mySecondObj = new MyClass();
console.log(myObj) // MyClass {myArr: Array[1]}
console.log(mySecondObj) // MyClass {myArr: Array[1]}