Solution of Program #RMJPQ2 on http://ronitmukherjee.com/javascript-practice-questions/#RMJPQ2

RMJPQ2.js

//JS Fiddle Link:- https://jsfiddle.net/mukherjeeronit/ac1nvp6j/

function sumOfAllEvenNumbers(arr) {
    var sum = 0;

    for (var i = 0; i < arr.length; i++) {
        isEven(arr[i], function(response) {
            if (response === true) {
                sum += arr[i];
            }
        });
    }

    return sum;
}

function isEven(num, callback) {
    if (num % 2 === 0) {
        callback(true);
    } else {
        callback(false);
    }
}



var arr = [10, 3, 9, 6, 11, 20];
var sum = sumOfAllEvenNumbers(arr);
console.log("sum of all even numbers = " + sum);