Functions in js.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>Functions</title>
</head>
<body>
    
    <input type="number" id="length" value="6"/>
    <input type="number" id="width" value="5"/>
    <div id="demo"></div>
    <button id="jack" onclick = "area()">Area</button>


    <script>
    

function area(){
    
    let  x=document.getElementById("length").value;
    let y=document.getElementById("width").value;

    let w= x * y;
    debugger;   // finding and removing an error
    document.getElementById("demo").innerHTML=w;
    
    
}


// let z,x;
// let u ;
// function area(z=10,x=10)
// {
// area=z*x;

// }
// console.log( area);


    </script>
</body>
</html>