Question

我想修改＆＃34;名称＆＃34;通过添加前缀＆＃34;与suggar＆＃34;并为成本增加+1。没有添加属性：＆＃34; coffee.sugar＆＃34;方法：＆＃34; this.toString＆＃34;

＆＃13;

function Coffe(name) {
        this.name = name;
        this.cost = function () {
            return 5;
        };
        this.toString = function () {
            return this.name + this.cost() + 'USD';
        }
    }
 var sugar = function () {
        coffe.sugar = "with sugar ";
      var cost = coffe.cost();
        coffe.cost = function () {
            return cost + 1;
        }
    };
 var coffe = new Coffe('Latte');
    sugar(coffe);
    console.log(coffe.cost());

＆＃13;

Answer 1

只需重新分配name属性：

function Coffe(name) {
        this.name = name;
        this.cost = function () {
            return 5;
        };
        this.toString = function () {
            return this.name + this.cost() + 'USD';
        }
    }
 var sugar = function (coffe) {
      coffe.name = "with sugar " + coffe.name;
      var cost = coffe.cost();
        coffe.cost = function () {
            return cost + 1;
        }
    };
 var coffe = new Coffe('Latte');
    sugar(coffe);
    console.log(coffe.name);
    console.log(coffe.cost());

Answer 2

你的sugar方法没有参数，但是你正在传递你的coffee实例。只需改变传递的实例的name属性，如下所示：

＆＃13;

function Coffe(name) {
        this.name = name;
        this.cost = function () {
            return 5;
        };
        this.toString = function () {
            return this.name + this.cost() + 'USD';
        }
    }
 var sugar = function (coffe) {
        coffe.name += " with sugar";
      var cost = coffe.cost();
        coffe.cost = function () {
            return cost + 1;
        }
    };
 var coffe = new Coffe('Latte');
    sugar(coffe);
    console.log(coffe.cost());
    console.log(coffe.name);

＆＃13;

如何修改构造函数的属性？

2 个答案: