index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #switch {
            height: 4em;
            width: 10em;
            background-color: coral;
        }
        #switch:hover {
            background-color: pink;

        }
    </style>
</head>
<body>
    <input type="button" id="switch" value="Light ON"> 
    <div id="feedback">on or off</div>
    
</body>
<script>
    function sendRequest(target, action, value="") {
        console.log("making request")
        let xR = new XMLHttpRequest();
        xR.onreadystatechange = function() {
            if (this.readyState == 4 && this.status == 200) {
                
                console.log("Server Response:", this.responseText);
                data = JSON.parse(this.responseText);
              
                feedback.innerText = data['status'];
                d.getElementById("switch").value = `Light ${data['status']}`;
            }
        }
        let data = {};
        data["action"] = action;
        data["value"] = value;
        xR.open("POST", target, true);
        xR.send(JSON.stringify(data));
    }
    d=document;
    switchstatus=true;
    onbutton=d.getElementById("switch");
    onbutton.addEventListener("click",toggle);

    function toggle(){
        feedback=d.getElementById("feedback");

        if (switchstatus){
            switchstatus=false;
            feedback.innerHTML="off"
            console.log("turning it off");
            sendRequest("led",action="OFF");
        } else {
            switchstatus=true;
            feedback.innerHTML="on"
            console.log("turning it on");
            sendRequest("led",action="ON");
        }
    }

</script>
</html>