A fun way to think about JS closures. From http://www.hongkiat.com/blog/javascript-jargon/

restaurantProcess.js

function order() {
    var food;   
    function waiter(order) {
        chef(order);
        return food;
    }
    function chef(order) {
        if (order === 'pasta') {
            food = ['pasta', 'gravy', 'seasoning'];
            cook();
        }
    }
    function cook() { food.push('cooked'); }
    return waiter;
}
var myOrder = order();
console.log(myOrder('pasta'));
// Array [ "pasta", "gravy", "seasoning", "cooked" ]