JS数组对象合并,a,b 合并为c

var a = [
  {id: 2, nickname: "韩信", checked: false},
  {id: 7, nickname: "刘邦", checked: true},
];
var b = [
  {id: 2, nickname: "韩信", checked: false},
  {id: 7, nickname: "刘邦", checked: false},
  {id: 8, nickname: "项羽", checked: false},
];

var ids = {}; // 用于跟踪已经存在的id

var c = a.concat(b).filter(item => {
  if (!ids[item.id]) { // 如果ids中不存在当前id，则将当前id添加到ids中，并保留该项
    ids[item.id] = true;
    return true;
  }
  return false; // 如果ids中已经存在当前id，则过滤掉该项
});

console.log(c);