<!DOCTYPE html>
<html>
<body>

<p>Click the button to loop through the indices of an array named "cars".</p>

<button onclick="myFunction()">Try it</button>

<p id="demo"></p>

<script>
function myFunction() {
    var cars = ["BMW", "Volvo", "Saab", "Ford"];
    var i;
    for (i = 0, len = cars.length, text = ""; i < len; i++) {
        text += cars[i] + "<br>";
    }
    document.getElementById("demo").innerHTML = text;
}
</script>

</body>
</html>