JAVASCRIPT FOR/IN LOOP EXAMPLE
Run 
<html>
    <body>
        <h2>for/in loop in JavaScript</h2>
        <p id="demo"></p>
        <script>
            let txt = '';
            // define an object
            let person = {fname:"ram", lname:"singh", age:89};
            let x;
            for(x in person)
            {
                // x is the key like fname, lname and age
                txt += person[x] + " ";
                
            }
            document.getElementById("demo").innerHTML = txt;
        </script>
    </body>
</html>