activity1.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        img{
            width: 100px;
        }
    </style>
</head>
<body>
    <img src="img/bulboff.gif">
<!--     
    <button onclick="onBulb()">On Bulb</button>
    <button onclick="offBulb()">Off Bulb</button> -->

    <button onclick="both()">Button(on-off)</button>


    <script>
        function onBulb(){
            document.querySelector('img').src = "img/bulbon.gif";
        }

        function offBulb(){
            document.querySelector('img').src = "img/bulboff.gif";
        }


        var count = 1;
        function both(){
            if(count%2==1){
                document.querySelector('img').src = "img/bulbon.gif";
            }
            else{
                document.querySelector('img').src = "img/bulboff.gif";
            }
            count++;
        }
        
    </script>
</body>
</html>