如何使用公共属性合并 javascript 中的对象元素数组

Question

     const data = [
  {
    date: "2021-05-17",
    meals: [{ name: "jon", breakFast: 1, lunch: 2, dinner: 2 }],
  },
  {
    date: "2021-05-17",
    meals: [{ name: "Bob", breakFast: 3, lunch: 4, dinner: 5 }],
  },
  {
    date: "2021-05-18",
    meals: [{ name: "Boo", breakFast: 3, lunch: 4, dinner: 5 }],
  },
];

I have an array of objects. There has different date and meals(array of objects). Is it possible to show all same date meals together?

Like this one.

  const data = [
  {
    date: "2021-05-17",
    meals: [
      { name: "jon", breakFast: 1, lunch: 2, dinner: 2 },
      { name: "Bob", breakFast: 3, lunch: 4, dinner: 5 },
    ],
  },
  {
    date: "2021-05-18",
    meals: [{ name: "Boo", breakFast: 3, lunch: 4, dinner: 5 }],
  },
];

Answer 1

 const data = [{ date: "2021-05-17", meals: [{ name: "jon", breakFast: 1, lunch: 2, dinner: 2 }], }, { date: "2021-05-17", meals: [{ name: "Bob", breakFast: 3, lunch: 4, dinner: 5 }], }, { date: "2021-05-18", meals: [{ name: "Boo", breakFast: 3, lunch: 4, dinner: 5 }], }, ]; let res = {}; data.forEach(x => { if (.res[x.date]) { res[x.date] = {..;x }. } else { res[x.date].meals = [...res[x.date],meals. ...x;meals]; } }). console.log(Object;values(res));

Answer 2

You need to iterate all the data and search if the result array contains the date. If not, create the new item with the date. Then just push the meals data inside.

 const data = [{date: "2021-05-17",meals: [{ name: "jon", breakFast: 1, lunch: 2, dinner: 2 }],},{date: "2021-05-17",meals: [{ name: "Bob", breakFast: 3, lunch: 4, dinner: 5 }],},{date: "2021-05-18",meals: [{ name: "Boo", breakFast: 3, lunch: 4, dinner: 5 }],},]; const result = []; data.forEach(d => { let i = result.findIndex(e => e.date === d.date) + 1 || result.push({date: d.date, meals: []}); result[i - 1].meals.push(...d.meals); }) console.log(result);