Sohail

function button_selection() {
    let colors = ["yellow", "blue", "red", "green"];
    let index = 0;
    $(".color").css("color", colors[index]);
    setInterval(() => {
        ++index;
        if (index >= colors.length) index = 0;
        $(".color").css("color", colors[index]);
    }, 1000);
}
setTimeout(button_selection, 0);

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<h1 class="color">Hello world, I love you all.</h1>