计算属性用法1

在一个计算器属性里可以完成各种复杂的逻辑,包括运算,函数调用等,只要最终返回一个结果就可以.

例: 下面示例展示的是在购物车内两个包裹的物品总价:

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>示例</title>

</head>
<body>

    <div id="app">
        总价: {{ prices }}
    </div>

    <script src="https://unpkg.com/vue/dist/vue.min.js"></script>

    <script>

        var app = new Vue({
            el: '#app',
            data: {
                package: [
                    {
                        name: 'iphone x',
                        price: 9000,
                        count: 2
                    },
                    {
                        name: 'ipad',
                        price: 4500,
                        count: 1
                    }
                ],
                package2: [
                    {
                        name: 'apple',
                        price: 3,
                        count: 5
                    },
                    {
                        name: 'hanana',
                        price: 2,
                        count: 10
                    }
                ]
            },
            computed: {
                prices: function () {
                    var prices = 0;
                    for (var i = 0; i < this.package.length; i++) {
                        prices += this.package[i].price * this.package[i].count;
                    }
                    for (var i = 0; i < this.package2.length; i++ ) {
                        prices += this.package2[i].price * this.package2[i].count;
                    }
                    return prices;
                }
            }
        })

    </script>

</body>
</html>

注: 当 package 或 package2 中的商品有任何变化, 比如购买数量变化或增删商品时,计算属性 prices 就会自动更新,视图中的总价也会自动变化.