JSFiddle - React, Tailwind, and code Playground

JavaScript

var array = [];

array["foo"] = "bar";
array["bar"] = "foo";
array.bin = function() { return "bin"; };

array[0] = "bar";
array[1] = "foo";
array[2] = "bin";
array[3] = "bat";

var props = 0;

for (key in array)
    props++;

document.write(array.length + "<br />" 
               + props + "<br />" 
               + (array.foo == array["foo"]) + "<br />" 
               + array.bar + "<br />"
               + array.bin());