javascript - 如何根据复杂性优化我的 JS 代码

Question

我有 2 个数组:

user = [
  { id: 33, first_name: 'Alex', last_name: 'Shelly' },
  { id: 23, first_name: 'Mike', last_name: 'Marley' }
]

selectedNotes = [
  { employee_id: 33, notes: 'test' },
  { employee_id: 109, notes: 'test1' }
]

我正在尝试查找 id 与 employee_id 匹配的用户的 firstname 和 lastname selectedNotes 数组。 (例如上述案例中的 Alex Shelly)。

我有:

for (let i = 0; i < user.length; i++) {
  for (let j = 0; j < selectedNotes.length; j++) {
    if (user[i].id == selectedNotes[j].employee_id) {
      selectedNotes.splice(j, 0, {
        by_name: user[i].first_name + ' ' + user[i].last_name
      }); // adding a new property in the array if the id matches
    }
  }
}

在优化方面有更好的方法吗？

Answer 1

我会创建一个Map对象并存储按id索引的用户，这样以后用户搜索会更高效

如果用户只需要一次并且用户数组不是那么大，我会执行 map /查找解决方案

const users = [
  {
    id: 33,
    first_name: 'Alex',
    last_name: 'Shelly'
  },
  {
    id: 23,
    first_name: 'Mike',
    last_name: 'Marley'
  }
];

const selectedNotes = [
  {
    employee_id: 33,
    notes: 'test'
  },
  {
    employee_id: 109,
    notes: 'test1'
  }
];

const usersMap = new Map();

for (const user of users) {
  usersMap.set(user.id, user);
}

const selectedNotesWithUser = selectedNotes.map(note => {
  const user = usersMap.get(note.employee_id);

  if (!user) {
    // Do you want to do something if there is no user?
    console.warn(`there is no user for employee id: ${note.employee_id}`);
  }

  return Object.assign(note, user);
});

console.log(selectedNotesWithUser);

// map & find
const selectedNotesWithUser2 = selectedNotes.map(note => {
  const user = users.find(user => user.id === note.employee_id);

  if (!user) {
    // Do you want to do something if there is no user?
    console.warn(`there is no user for employee id: ${note.employee_id}`);
  }

  return Object.assign(note, user);
});

console.log(selectedNotesWithUser2);