javascript - Angular 6，从对象中获取新对象

Question

我的 list

defaultUsers: any[] = [
  {id: 31, name: "A"},
  {id: 32, name: "B"},
  {id: 33, name: "C"},
  {id: 34, name: "D"},
  {id: 35, name: "E"},
  {id: 36, name: "F"},
  {id: 37, name: "G"},
  {id: 38, name: "H"},
];

onlineUsers: any[]= [
  {userid: 31, platform: 'web'},
  {userid: 31, platform: 'mobil'},
  {userid: 32, platform: 'mobil'},
];

users: any[];

我的函数，

test(){
  let isOnline: boolean, isWeb: boolean, isMobile: boolean;

   this.users = this.defaultUsers.map(user=>{
    isOnline = this.onlineUsers.some((onlineUser: { userid: number; })=> onlineUser.userid == user.id);      

    -- ( ! help-> I could not build the structure in my head) --

    return {...user, online: isOnline }
   });

   console.log(this.users)
  }

我想要得到:

[
{id: 31, name: "A", mobile: true, web: true, online: true },
{id: 32, name: "B", mobile: true, web: false, online: true },
{id: 33, name: "C", mobile: false, web: false, online: false },
{id: 34, name: "D", mobile: false, web: false, online: false },
{id: 35, name: "E", mobile: false, web: false, online: false },
{id: 36, name: "F", mobile: false, web: false, online: false },
{id: 37, name: "G", mobile: false, web: false, online: false },
{id: 38, name: "H", mobile: false, web: false, online: false },
]

如何才能以最准确和最高效的方式确保这一点？你能帮助我吗？我想用我手中的物体得到我想要的物体。

Answer 1

您可以使用 .filter() 从 onlineUsers 检索用户并查找平台类型:

  test() {
    let isOnline: boolean, isWeb: boolean, isMobile: boolean;

    this.users = this.defaultUsers.map((u) => {
      const users = this.onlineUsers.filter((onlineUser: { userid: number; platform: string; }) => onlineUser.userid == u.id);

      const isOnline = !!users.length;
      const isWeb = users.some((usr) => usr.userid === u.id && usr.platform === 'web');
      let isMobile = users.some((usr) => usr.userid === u.id && usr.platform === 'mobil');

      return { ...u, online: isOnline, web: isWeb, mobile: isMobile }
    });

    console.log(this.users)
  }

现场演示:here