javascript - array[id].method 不起作用？

Question

我有一个 for 循环运行，遍历数组中的每个项目并使用一个方法执行数组项目。由于某种原因，这返回为未定义，但没有 .method 它工作正常。这是我的代码:

    var people = ["susan", "david", "bob", "verity", "rhys", "charles"]
    
        function characters(name, sex) {
            this.name = name;
            this.sex = sex;
        }
    
    var susan = new characters("Susan", "Female");
    var david = new characters("David","Male");
    var bob = new characters("Bob","Male");
    var verity = new characters("Verity","Female");
    var rhys = new characters("Rhys","Male");
    var charles = new characters("Charles","Male");
    
    characters.prototype.info = function() {
        alert("Hi my name is " + this.name + " and I am a " + this.sex);
    }
    
    
    for(i = 0; i < people.length;i++) {
        people[i].info();
    }

预期的行为是针对每个 Angular 色显示“嗨，我的名字是 [name]，我是 [sex]”的警告，但实际上没有任何反应。

Answer 1

你的问题是你的数组是字符串数组而不是 characters 对象数组，这是你的循环所期望的。

people[i] 循环的每次迭代不是您创建的对象，而是包含每个对象的变量名称的字符串。因此，调用您的 info() 方法将不会成功，因为您是在字符串而不是 characters 对象上调用它。

删除引号并重新排列代码，使数组声明位于变量声明之后，这样就可以正常工作:

function characters(name, sex) {
  this.name = name;
  this.sex = sex;
}

characters.prototype.info = function() {
  alert("Hi my name is " + this.name + " and I am a " + this.sex);
}

var susan = new characters("Susan", "Female");
var david = new characters("David", "Male");
var bob = new characters("Bob", "Male");
var verity = new characters("Verity", "Female");
var rhys = new characters("Rhys", "Male");
var charles = new characters("Charles", "Male");

var people = [susan, david, bob, verity, rhys, charles];

for (i = 0; i < people.length; i++) {
  people[i].info();
}