Get Programming with JavaScript - Listing 8.11

Get Programming with JavaScript - Listing 8.11

Listing 8.11 - Finding the total shopping bill

var getTotalBill = function (itemCosts, itemCounts) {
    var total = 0;

    itemCosts.forEach(function (cost, i) {
        total += cost * itemCounts[i];
    });

    return total;
};

var costs = [ 1.99, 4.95, 2.50, 9.87 ];
var numOfEach = [ 2, 1, 5, 2 ];

console.log("The total cost is $" + getTotalBill(costs, numOfEach));

Further Adventures

Listing 8.11 - Finding the total shopping bill - Task 1

Add an extra item to the shopping trip.

var getTotalBill = function (itemCosts, itemCounts) {
    var total = 0;

    itemCosts.forEach(function (cost, i) {
        total += cost * itemCounts[i];
    });

    return total;
};

var costs = [ 1.99, 4.95, 2.50, 9.87, 6.95 ];
var numOfEach = [ 2, 1, 5, 2, 1 ];

console.log("The total cost is $" + getTotalBill(costs, numOfEach));

You could just increase one of the elements in the numOfEach array to add an extra item.

Listing 8.11 - Finding the total shopping bill - Task 2

Change the function so that forEach iterates over itemCounts instead of itemCosts.

var getTotalBill = function (itemCosts, itemCounts) {
    var total = 0;

    itemCounts.forEach(function (count, i) {
        total += count * itemCosts[i];
    });

    return total;
};

var costs = [ 1.99, 4.95, 2.50, 9.87, 6.95 ];
var numOfEach = [ 2, 1, 5, 2, 1 ];

console.log("The total cost is $" + getTotalBill(costs, numOfEach));

Listing 8.11 - Finding the total shopping bill - Tasks 3&4

Create a single array of objects with cost and numberBought properties.
Update getTotalBill to accept a single array of items.

var getTotalBill = function (items) {
    var total = 0;

    items.forEach(function (item) {
        total += item.cost * item.numberBought;
    });

    return total;
};

var items = [
    { cost: 1.99, numberBought: 2 },
    { cost: 4.95, numberBought: 1 },
    { cost: 2.50, numberBought: 5 },
    { cost: 9.87, numberBought: 2 }
];

console.log("The total cost is $" + getTotalBill(items));