Typescript合并2个数组，如果它们具有相同的id，则增加数量

interface Item {
  id: number;
  quantity: number;
}

function mergeArrays(arr1: Item[], arr2: Item[]): Item[] {
  const mergedArray: Item[] = [];

  // 将arr1中的元素添加到mergedArray中
  for (const item of arr1) {
    const existingItem = mergedArray.find(i => i.id === item.id);
    if (existingItem) {
      existingItem.quantity += item.quantity;
    } else {
      mergedArray.push({ id: item.id, quantity: item.quantity });
    }
  }

  // 将arr2中的元素添加到mergedArray中
  for (const item of arr2) {
    const existingItem = mergedArray.find(i => i.id === item.id);
    if (existingItem) {
      existingItem.quantity += item.quantity;
    } else {
      mergedArray.push({ id: item.id, quantity: item.quantity });
    }
  }

  return mergedArray;
}

// 示例用法
const array1: Item[] = [
  { id: 1, quantity: 3 },
  { id: 2, quantity: 5 },
  { id: 3, quantity: 2 }
];

const array2: Item[] = [
  { id: 2, quantity: 2 },
  { id: 3, quantity: 4 },
  { id: 4, quantity: 1 }
];

const mergedArray = mergeArrays(array1, array2);
console.log(mergedArray);