JSFiddle - React, Tailwind, and code Playground

HTML

<span>a</span><span>b</span><span>c</span><span>d</span>

JavaScript

var word = 'abcd';
var matches = [0, 1, 1, 0];

$(document).ready(function() {
  for(var i = 0; i <= word.length; i++){
    $("span").eq(i).css('color', matches[i] ? 'green':'red');
  };
});