JSFiddle - React, Tailwind, and code Playground

JavaScript

var distinctCtyNames = ['Toronto', 'Moscow', 'New York'];

for (ctyKey in distinctCtyNames) // changed to ctyKey
{
    var ctyName = distinctCtyNames[ctyKey]; // get ctyName
    var element = document.createElement('div');
    element.id = ctyName;
    element.innerText = ctyName;
    document.body.appendChild(element);
}