JSFiddle - React, Tailwind, and code Playground

HTML

<input id="field">
<div id="message"></div>

JavaScript

let field = document.querySelector('#field');
let message = document.querySelector('#message');
var cities = [];

field.addEventListener('blur', function() {

  if (field.value[0] !== cities[i][0] && !cities[i]) {
    cities.push(this.value);
    console.log(cities);
  }




})