合并对象数组，合并键值相同，保持唯一值

function mergeArrays(arr1, arr2) {
  // 创建一个新的数组存放合并结果
  let merged = [...arr1];

  for (let obj of arr2) {
    // 判断对象在合并后的数组中是否存在相同键值
    let exist = merged.some(item => item.key === obj.key);

    if (!exist) {
      merged.push(obj);
    }
  }

  return merged;
}

// 示例数据
let arr1 = [
  { key: 'A', value: 1 },
  { key: 'B', value: 2 },
];
let arr2 = [
  { key: 'B', value: 3 },
  { key: 'C', value: 4 },
];

let result = mergeArrays(arr1, arr2);
console.log(result);

const _ = require('lodash');

// 示例数据
let arr1 = [
  { key: 'A', value: 1 },
  { key: 'B', value: 2 },
];
let arr2 = [
  { key: 'B', value: 3 },
  { key: 'C', value: 4 },
];

let result = _.uniqBy(_.concat(arr1, arr2), 'key');
console.log(result);