undefined-3

undefined-3

<!DOCTYPE html>
<html>
<head>
<title>Welcome to LearnKode - A code learning platform</title>
</head>
<body>
<p>Click the button to check whether the variables have been assigned a value or not.</p>
<button onclick="checkUndefined()">Click it</button>
<p id="sample"></p>
<script>
function checkUndefined() {
    var x1 = "myFunction";
    var x2;
    if (x1 === undefined) {
        txt1 = "x1 is undefined";
    } else {
        txt1 = "x1 is defined";
    }
    if (x2 === undefined) {
        txt2 = "x2 is undefined";
    } else {
        txt2 = "x2 is defined";
    }
    txt = txt1 + "<br>" + txt2;
    document.getElementById("sample").innerHTML = txt;
}
</script>
</body>
</html>

Output