js 对象数组去重

1.使用Array.filter()和Array.findIndex()方法

const arr = [
  {id: 1, name: 'John'},
  {id: 2, name: 'Mary'},
  {id: 1, name: 'John'},
  {id: 3, name: 'Peter'}
];

const uniqueArr = arr.filter((obj, index, self) => {
  return index === self.findIndex(t => (
    t.id === obj.id && t.name === obj.name
  ));
});

console.log(uniqueArr); // [{id: 1, name: 'John'}, {id: 2, name: 'Mary'}, {id: 3, name: 'Peter'}]

2.使用Map对象

const arr = [
  {id: 1, name: 'John'},
  {id: 2, name: 'Mary'},
  {id: 1, name: 'John'},
  {id: 3, name: 'Peter'}
];

const map = new Map();
arr.forEach(obj => {
  const key = obj.id + '|' + obj.name;
  if (!map.has(key)) {
    map.set(key, obj);
  }
});

const uniqueArr = Array.from(map.values());

console.log(uniqueArr); // [{id: 1, name: 'John'}, {id: 2, name: 'Mary'}, {id: 3, name: 'Peter'}]

3.如果你确定每个属性都是基本类型（比如字符串、数字、布尔值等）并且没有任何内部对象或函数，那么可以省略比较阶段。此时可以使用JSON.stringify()方法将每个对象转换为字符串，然后使用Set对象去重。

const arr = [
  {id: 1, name: 'John'},
  {id: 2, name: 'Mary'},
  {id: 1, name: 'John'},
  {id: 3, name: 'Peter'}
];

const uniqueArr = Array.from(new Set(arr.map(obj => JSON.stringify(obj)))).map(str => JSON.parse(str));

console.log(uniqueArr); // [{id: 1, name: 'John'}, {id: 2, name: 'Mary'}, {id: 3, name: 'Peter'}]

4.