let arr = [
  { name: 'zs', age: 15, happy: ['唱歌', '玩游戏'] },
  { name: 'ls', age: 15, happy: ['玩游戏'] },
  { name: 'zs', age: 15, happy: ['学习', '划水'] },
];

function test(arr) {
  let _obj = {};
  let _arr = [];
  if (!arr.length) return;
  arr.map((item) => {
    _obj[item.name]?.happy.length
      ? (_obj[item.name].happy = [..._obj[item.name].happy, ...item.happy])
      : (_obj[item.name] = item);
  });
  _arr = Object.values(_obj);
  return _arr;
}

let arr2 = test(arr);
console.log(arr2);

let arr = [
  { name: 'zs', age: 15, happy: ['唱歌', '玩游戏'] },
  { name: 'ls', age: 15, happy: ['玩游戏'] },
  { name: 'zs', age: 15, happy: ['学习', '划水'] },
];

function test(arr) {
  let _obj = {};
  let _arr = [];
  if (arr.length)
    arr.map((item) => {
      _obj[item.name]?.happy.length
        ? (_obj[item.name].happy = _obj[item.name].happy.concat(item.happy))
        : (_obj[item.name] = item);
    });
  _arr = Object.values(_obj);
  return _arr;
}

let arr2 = test(arr);
console.log(arr2);