Question

我有简单的JavaScript代码，但警报在任何浏览器中都不起作用我的代码是：

 function ChangeText(){
    document.getElementById("p1").innerHTML = "dorood";
    }
    var students = [student1, student2, student3];
    var student1 ={FirstName:"saeed",LastNmae:"alavi",Age:"1992"};
    var student2 = { FirstName: "mohammad", LastNmae: "alavi", Age: "1992" };
    var student3 = { FirstName: "hosein", LastNmae: "alavi", Age: "1992" };
    alert(students[1].FirstName);

Answer 1

你只需要移动var students = [student1，student2，student3];你所指的变量，没有被分配。

＆＃13;

    var student1 ={FirstName:"saeed",LastNmae:"alavi",Age:"1992"};
    var student2 = { FirstName: "mohammad", LastNmae: "alavi", Age: "1992" };
    var student3 = { FirstName: "hosein", LastNmae: "alavi", Age: "1992" };
    var students = [student1, student2, student3];
    
    alert(students[1].FirstName);

＆＃13;

Answer 2

只有在创建单个对象后才能创建数组。

＆＃13;

function ChangeText() {
  document.getElementById("p1").innerHTML = "dorood";
}

var student1 = {
  FirstName: "saeed",
  LastNmae: "alavi",
  Age: "1992"
};
var student2 = {
  FirstName: "mohammad",
  LastNmae: "alavi",
  Age: "1992"
};
var student3 = {
  FirstName: "hosein",
  LastNmae: "alavi",
  Age: "1992"
};
var students = [student1, student2, student3];
alert(students[1].FirstName);

＆＃13;

Answer 3

您必须收到明确的错误

“未捕获的TypeError：无法读取未定义的属性'FirstName'”

在初始化student1,student2...数组时使用它们之前定义变量students。

function ChangeText() {
  document.getElementById("p1").innerHTML = "dorood";
}

var student1 = {
  FirstName: "saeed",
  LastNmae: "alavi",
  Age: "1992"
};
var student2 = {
  FirstName: "mohammad",
  LastNmae: "alavi",
  Age: "1992"
};
var student3 = {
  FirstName: "hosein",
  LastNmae: "alavi",
  Age: "1992"
};

var students = [student1, student2, student3];
console.log(students[1].FirstName);

javascript：alert在任何浏览器中都不起作用

3 个答案: