javascript：警報在任何瀏覽器中均不起作用，為什么

Question

我有簡單的JavaScript代碼，但該警報在任何瀏覽器中均不起作用，我的代碼是：

 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

您只需要移動var students = [student1，student2，student3]； 您所指代的變量未分配。

  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); 

Answer 2

您只能在創建單個對象之后創建數組。

 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); 

Answer 3

您必須得到以下明顯的錯誤

“未捕獲的TypeError：無法讀取未定義的屬性'FirstName'”

在初始化students數組之前使用變量student1,student2...

 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);