无法将项目添加到数组

Question

如何将新项目添加到数组？我正在尝试添加一个项目，但它返回错误。请查看下面的屏幕截图和代码。

屏幕截图

JavaScript代码

var roles = [{id: 8, display_name: "test", description: "test", created_at: "2020-02-20 11:34:22", updated_at: "2020-02-20 11:34:22"}
8: {id: 9, display_name: "ASDASD", description: "ADASD", created_at: "2020-02-20 11:39:08", updated_at: "2020-02-20 11:39:08"}
9: {id: 10, display_name: "Test1", description: "test1", created_at: "2020-02-20 11:44:01", updated_at: "2020-02-20 11:44:01"}
10: {id: 11, display_name: "Test2", description: "test2", created_at: "2020-02-21 04:18:49", updated_at: "2020-02-21 04:18:49"}
11: {id: 12, display_name: "Test3", description: "test3", created_at: "2020-02-21 06:56:52", updated_at: "2020-02-21 06:56:52"}
12: {id: 13, display_name: "Test4", description: "test4", created_at: "2020-02-21 07:00:32", updated_at: "2020-02-21 07:00:32"}];


this.roles.id = 12;
this.roles.display_name = 'Mod';
this.roles.description = 'mod';
this.roles.created_at = '2020-02-21 07:12:50';
this.roles.updated_at = '2020-02-21 07:12:50';

错误

TypeError：无法设置未定义的属性“ id”

我想要的东西：

将项目添加到上面的屏幕截图中的数据中。

注意

我正在使用vueJS，并且已经在roles对象中设置了data{}数据。

Answer 1

看起来this.roles可能是您正在记录的项目的数组，对吧？

因此，通过设置this.roles.id = 12;，您试图设置数组的id属性，而不是使用这些属性向数组添加新项。

尝试一下

var newRole = {
  id: 12,
  display_name: 'Mod',
  description: 'mod',
  created_at: '2020-02-21 07:12:50',
  updated_at: '2020-02-21 07:12:50'
};

this.roles.push(newRole);

这是我最好的猜测。您确实应该上传有关该问题的更多信息：

• 您在该屏幕快照中登录了什么？
• 您当前的方法无效吗？

Answer 2

这是一个解决方案，
我已经创建了示例角色对象数组，
创建了一个要添加的新对象，
然后将新对象添加到数组中。

let roles = [
    {
        "id" : 1,
        "display_name" : "One",
        "description" : "One desc",
        "created_at" : "2020-02-21 01:01:01",
        "updated_at" : "2020-02-21 01:01:01"
    },
    {
        "id" : 2,
        "display_name" : "Two",
        "description" : "Two desc",
        "created_at" : "2020-02-21 01:01:01",
        "updated_at" : "2020-02-21 01:01:01"
    }
];

let newRole = {};
newRole.id = 3;
newRole.display_name = "Three";
newRole.description = "Three desc";
newRole.created_at = "2020-02-21 01:01:01";
newRole.updated_at = "2020-02-21 01:01:01";

roles.push(newRole);

您正在直接尝试将对象添加到数组中，
如果您指定索引，也可以这样做

Answer 3

这是json元素的数组。您需要先制作一个元素，然后将其放入这样的角色数组中。

let newElement = {id:12, display_name :'Mod', description : 'mod', created_at:'2020-02-21 07:12:50', updated_at:'2020-02-21 07:12:50'}
this.roles.push(newElement)

Answer 4

由于使用了“ this”，它是指窗口而不是对象，因此出现了未定义的错误。

您可以在已经获得答案的情况下手动添加它，或者可以使用Class代替，我认为这样做会更好，我认为使用所有这些代码复制都不好，这就是我的解决方案：< / p>

const roles = [{ id: 8, display_name: "test", description: "test", created_at: "2020-02-20 11:34:22", updated_at: "2020-02-20 11:34:22" },
{ id: 9, display_name: "ASDASD", description: "ADASD", created_at: "2020-02-20 11:39:08", updated_at: "2020-02-20 11:39:08" },
{ id: 10, display_name: "Test1", description: "test1", created_at: "2020-02-20 11:44:01", updated_at: "2020-02-20 11:44:01" },
{ id: 11, display_name: "Test2", description: "test2", created_at: "2020-02-21 04:18:49", updated_at: "2020-02-21 04:18:49" },
{ id: 12, display_name: "Test3", description: "test3", created_at: "2020-02-21 06:56:52", updated_at: "2020-02-21 06:56:52" },
{ id: 13, display_name: "Test4", description: "test4", created_at: "2020-02-21 07:00:32", updated_at: "2020-02-21 07:00:32" }];

class Role {
    id;
    display_name;
    description;
    created_at;
    updated_at;
    constructor(id, display_name, description, created_at, updated_at) {
        this.id = id;
        this.display_name = display_name;
        this.description = description;
        this.created_at = created_at;
        this.updated_at = updated_at;
    }
}

const role1 = new Role(14, "asdas", "asdasd", "2020-02-21", "2020-02-21");
roles.push(role1);
const role2 = new Role(15, "asdasas", "assdasd", "2020-02-21", "2020-02-21");
roles.push(role2);