JSFiddle - React, Tailwind, and code Playground

HTML

<div id="chinchilla"></div>

JavaScript

var iterable = { add:null, length:null };
var chin = document.getElementById('chinchilla');
for (prop in iterable) {
    chin.innerHTML += prop + ": " + chin[prop] + "<br>\n";
}

chin.innerHTML += "<hr>\n";

var itarray = ["add", "length"], i, itl = itarray.length, prop;
for (i = 0; i < itl; i++) {
    prop = itarray[i];
    chin.innerHTML += prop + ": " + chin[prop] + "<br>\n";
}