fn_return.js

function sum(x, y) {
    var z = x + y;
    return z; // return back the value of 
    // z
}

var zz = sum(5 , 6);
// sum(5 , 6) evaluates to 11
// sum(10, 20) evaluates to 30
console.log(zz);

zz = sum(10, 20);
console.log(zz);