const colors = ['yellow', 'green', 'blue', 'red']
const INTERVAL = 200;
colors.forEach((color, index) => {
setTimeout(() => { $('.color').css("color", colors[index]) }, index*INTERVAL)
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.0/jquery.min.js"></script>
<h1 class="color">Hello world!<h1>
