js 数组合并

1.简单类型数组

ES6
array1.push(...array2) // => don't remove duplication
OR
[...array1,...array2] // => don't remove duplication
OR
[...new Set([...array1 ,...array2])]; // => remove duplication

2.对象数组

（1）方法一

var initialData = [{
    'ID': 1,
    'FirstName': 'Sally'
  },
  {
    'ID': 2,
    'FirstName': 'Jim'
  },
  {
    'ID': 3,
    'FirstName': 'Bob'
  }
];

var newData = [{
    'ID': 2,
    'FirstName': 'Jim'
  },
  {
    'ID': 4,
    'FirstName': 'Tom'
  },
  {
    'ID': 5,
    'FirstName': 'George'
  }
];

var ids = new Set(initialData.map(d => d.ID));
var merged = [...initialData, ...newData.filter(d => !ids.has(d.ID))];

console.log(merged);

（2）方法二

const oldData = [
  { id: 1, name: 'John' },
  { id: 2, name: 'Jane' },
  { id: 3, name: 'Mike' },
];

const newData = [
  { id: 2, name: 'Jane' },
  { id: 4, name: 'Rick' },
  { id: 5, name: 'Jim' },
];

const usersMap = new Map();

oldData.forEach(user => usersMap.set(user.id, user));

newData.forEach(user => {
  const exists = usersMap.has(user.id);
  
  if (!exists) {
    usersMap.set(user.id, user);
  }
})

usersMap.forEach(user => console.log(user))