JSFiddle - React, Tailwind, and code Playground

HTML

<div id="foo">irrelevant content</div>

CSS

.red {
  color: red;
}
.blue {
  color: blue;
}
.green {
  color: green;
}

JavaScript

var post_array = [ "abc", "123", "xyz" ];
var class_array = [ "red", "blue", "green" ];

var interval = 2000;
var i = 0;
var max = post_array.length;
var id ="#foo";

$(id).html(post_array[0]);
$(id).removeClass().addClass(class_array[0]);

setInterval( function(){
	++i;
	$(id).fadeOut("slow", function() {
  	$(id).html(post_array[i%max]).fadeIn("slow");
  	$(id).removeClass().addClass(class_array[i%max]);
  });
}, interval);