Array数组中查询相同项

方法一：把没有的项目显示出来

let A = [
  { id: 1, name: 'John' },
  { id: 2, name: 'Jane' },
  { id: 3, name: 'Doe' }
];
 
let B = [
  { id: 2, age: 25 },
  { id: 3, age: 30 }
];
 
A = A.map(aItem => {
  const bItem = B.find(bItem => bItem.id === aItem.id);
  return { ...aItem, ...bItem };
});
 
console.log(A);

打印出来的数据：把没有的项去掉

{ id: 1, name: 'John' },
{ id: 2, name: 'Jane', age: 25 },
{ id: 3, name: 'Doe', age: 30 }

方法二：

let A = [ { id: 1, name: 'John' }, { id: 2, name: 'Jane' }, { id: 3, name: 'Doe' } ];
const B = [{ id: 1, age: 25 }, { id: 2, age: 30 }, { id: 3, age: 22 }];
 
const mergeById = (arr1, arr2) => {
  return arr2.reduce((acc, current) => {
    const foundItem = arr1.find(item => item.id === current.id);
    if (foundItem) {
      acc.push({ ...foundItem, ...current });
    }
    return acc;
  }, []);
};
 
const mergedArray = mergeById(A, B);
console.log(mergedArray);

打印出来的数据：

{ id: 1, name: 'John', age: 25 },
{ id: 2, name: 'Jane', age: 30 }