How can I switch between two background-colors using js setinterval( )

Try this approach,

var i = 0;function change() { var doc = document.getElementById("background"); var color = ["black", "blue", "brown", "green"]; doc.style.backgroundColor = color[i]; i = (i + 1) % color.length;}setInterval(change, 1000);

<div id="background">&nbsp</div>