Question

我有一个for循环运行，遍历我的数组中的每个项目并使用方法执行数组项目。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，每个角色都会发出一条警告：“我的名字是[姓名]而我是[性别]”，但没有任何反应。

Answer 1

实际上，你需要数组中的字符，而不是字符串。这就是为什么它不起作用的原因。你正在循环遍历字符串数组试图调用它们的info函数，但是string没有实现info函数。创建角色后，您需要将它们添加到阵列中，然后您可以循环调用它们以获取所需的警报。

＆＃13;

    
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);
    }
    
    var people = [susan, david, bob, verity, rhys, charles];
    
    for(i = 0; i < people.length;i++) {
        people[i].info();
    }

＆＃13;

Answer 2

people是字符串的数组，而不是对象。

移动此行：

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

所以在之后是你声明并为变量赋值的行。

然后删除引号，这样就有变量而不是字符串文字。

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

Answer 3

您的问题是您的数组是一个字符串数组而不是characters个对象的数组，这正是您的循环所期望的。

对于循环的每次迭代，

people[i]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info()方法将失败，因为您在字符串而不是characters对象上调用它。

删除引号并重新排列代码，以便在变量声明之后出现数组声明，并且它将正常工作：

＆＃13;

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();
}

＆＃13;

Answer 4

people是一个字符串数组。数组中的字符串“suzan”与您进一步声明的变量suzan之间没有关系。而是尝试将对象本身放入数组中：

    
        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");
    
    var people = [susan, david, bob, verity, rhys, charles];

    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();
    }

如果没有每个人的所有特定变量，您甚至可以直接将字符创建的结果放入数组中：

    function characters(name, sex) {
            this.name = name;
            this.sex = sex;
        }

    var people = [
       new characters("Susan", "Female"),
       new characters("David","Male"),
       new characters("Bob","Male"),
       new characters("Verity","Female"),
       new characters("Rhys","Male"),
       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();
    }

javascript - array [id] .method不工作？

4 个答案: