Untitled

<!DOCTYPE html>
<html>
    <body>

        <script>

            function changeImg() {


                if (document.getElementById("cycle").src == "fox.jpg")
                {
                    document.getElementById("cycle").src = "hawk.jpg";
                }
                else
                {
                    document.getElementById("cycle").src = "ant.jpg";
                }

            }
        </script>

        <button onclick = "changeImg()">change image</button>

        <img id ="cycle" src ="fox.jpg"/>

    </body>
</html>