MVVM架构~knockoutjs实现简单的购物车

概念相关

购物车相信大家都用过，很方便，可以将多个商品添加到购物车，并且可以修改购买商品的数据，当然为了用户体验好，在修改数据时，你的价格也会出现变化的，这使用JS可以实现，但我认为，代码量挺大的，而使用knockoutjs可以大大减少代码量，而且更重要的是，当前台页面有所调整时，这个JS只需要简单调整，而不需要改后台代码！

代码相关

下面看一下实现简单购物车的代码

1 View部分

 <table>
        <thead>
            <tr>
                <th>商品</th>
                <th>单价</th>
                <th>数量</th>
                <th>小计</th>
                <th></th>
            </tr>
        </thead>
        <tbody data-bind="foreach:lines">
            <tr>
                <td data-bind="with:product">
                    <span data-bind="text:name"></span></td>
                <td data-bind="with:product"><span data-bind='text:formatCurrency(price)' /></td>
                <td>
                    <input data-bind='visible: product, value: productCount, valueUpdate: "afterkeydown"' />
                </td>
                <td><span data-bind="visible:product,text:formatCurrency(subtotal())"></span></td>
                <td><a href='#' data-bind='click: $parent.removeLine'>Remove</a></td>
            </tr>
        </tbody>
    </table>
    <p class='grandTotal'>
        Total value: <span data-bind='text: grandTotal()'></span>
    </p>
    <button data-bind='click: addLine'>Add product</button>

2 JS部分

 <script type="text/ecmascript">
        function formatCurrency(value) {
            return "￥" + value;
        }
        var Product = function (id, name, price) {
            self = this;
            self.id = id;
            self.name = name;
            self.price = price;
        }
        var CartItem = function (product) {
            self = this;

            self.product = ko.observable(product);
            self.productCount = ko.observable(1);

            self.subtotal = ko.dependentObservable(function () {
                return this.product() ? this.product().price * parseInt("0" + this.productCount(), 10) : 0;
            }.bind(self));
        };
        var CartList = function () {
            var self = this;
            self.lines = ko.observableArray([new CartItem(new Product(1, "test1", 100))]);

            self.addLine = function () { self.lines.push(new CartItem(new Product(2, "test2", 200))) };

            self.removeLine = function (line) { self.lines.remove(line) };

            self.grandTotal = ko.computed(function () {
                var total = 0;
                $.each(self.lines(), function () { total += this.subtotal(); })
                return total;
            });
        };
        ko.applyBindings(new CartList());

    </script>

3 有图有真相

完成代码如下

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title></title>
    <script src="jquery-1.7.1.min.js" type="text/javascript"></script>
    <script src="knockout-2.1.0.js" type="text/javascript"></script>

</head>
<body>
    <table>
        <thead>
            <tr>
                <th>商品</th>
                <th>单价</th>
                <th>数量</th>
                <th>小计</th>
                <th></th>
            </tr>
        </thead>
        <tbody data-bind="foreach:lines">
            <tr>
                <td data-bind="with:product">
                    <span data-bind="text:name"></span></td>
                <td data-bind="with:product"><span data-bind='text:formatCurrency(price)' /></td>
                <td>
                    <input data-bind='visible: product, value: productCount, valueUpdate: "afterkeydown"' />
                </td>
                <td><span data-bind="visible:product,text:formatCurrency(subtotal())"></span></td>
                <td><a href='#' data-bind='click: $parent.removeLine'>Remove</a></td>
            </tr>
        </tbody>
    </table>
    <p class='grandTotal'>
        Total value: <span data-bind='text: grandTotal()'></span>
    </p>
    <button data-bind='click: addLine'>Add product</button>
    <script type="text/ecmascript">
        function formatCurrency(value) {
            return "￥" + value;
        }
        var Product = function (id, name, price) {
            self = this;
            self.id = id;
            self.name = name;
            self.price = price;
        }
        var CartItem = function (product) {
            self = this;

            self.product = ko.observable(product);
            self.productCount = ko.observable(1);

            self.subtotal = ko.dependentObservable(function () {
                return this.product() ? this.product().price * parseInt("0" + this.productCount(), 10) : 0;
            }.bind(self));
        };
        var CartList = function () {
            var self = this;
            self.lines = ko.observableArray([new CartItem(new Product(1, "test1", 100))]);

            self.addLine = function () { self.lines.push(new CartItem(new Product(2, "test2", 200))) };

            self.removeLine = function (line) { self.lines.remove(line) };

            self.grandTotal = ko.computed(function () {
                var total = 0;
                $.each(self.lines(), function () { total += this.subtotal(); })
                return total;
            });
        };
        ko.applyBindings(new CartList());

    </script>
</body>
</html>