如何从嵌套对象重新计算 object 的数组？

Question

I have an array of objects where Citems is an array of Objects. Each object has status on or off and time.

[
{
  Chapter: [
    {
      Cname: 'chapter 1',
      Citems: [{status: 'on', time: 30},{status: 'on', time: 60}],
      
    },
    {
      Cname: 'chapter 2',
      Citems: [{status: 'on', time: 30},{status: 'off', time: 60}]
    }
  ],
  name: 'Something',
  description: 'jfdgljfgdfjgldfkjglfd'
},{
  Chapter: [
    {
      Cname: 'chapter 1',
      Citems: [{status: 'on', time: 30},{status: 'on', time: 60}],
      
    },
    {
      Cname: 'chapter 2',
      Citems: [{status: 'on', time: 30},{status: 'off', time: 60}]
    }
  ],
  name: 'Something',
  description: 'jfdgljfgdfjgldfkjglfd'
},{
  Chapter: [
    {
      Cname: 'chapter 1',
      Citems: [{status: 'on', time: 30},{status: 'on', time: 60}],
      
    },
    {
      Cname: 'chapter 2',
      Citems: [{status: 'on', time: 30},{status: 'off', time: 60}]
    }
  ],
  name: 'Something',
  description: 'jfdgljfgdfjgldfkjglfd'
}
]

I want to generate an array or object from it that show total time for each status like below

[{
on: 120,
off: 60
},
{
on: 120,
off: 60
},
{
on: 120,
off: 60
}]

I tried to use map and reduce in it by not getting the derired result

Answer 1

You were on the right track using map() and reduce() . An additional call to flatMap() and some destructuring brings it all together:

const result = data.map(({ Chapter }) => Chapter
  .flatMap(({ Citems }) => Citems)
  .reduce((a, { status, time }) => ({
    ...a,
    [status]: (a[status] || 0) + time
  }), {})
);

---

Complete snippet:

 const data = [{ Chapter: [{ Cname: 'chapter 1', Citems: [{ status: 'on', time: 30 }, { status: 'on', time: 60 }], }, { Cname: 'chapter 2', Citems: [{ status: 'on', time: 30 }, { status: 'off', time: 60 }] } ], name: 'Something', description: 'jfdgljfgdfjgldfkjglfd' }, { Chapter: [{ Cname: 'chapter 1', Citems: [{ status: 'on', time: 30 }, { status: 'on', time: 60 }], }, { Cname: 'chapter 2', Citems: [{ status: 'on', time: 30 }, { status: 'off', time: 60 }] } ], name: 'Something', description: 'jfdgljfgdfjgldfkjglfd' }, { Chapter: [{ Cname: 'chapter 1', Citems: [{ status: 'on', time: 30 }, { status: 'on', time: 60 }], }, { Cname: 'chapter 2', Citems: [{ status: 'on', time: 30 }, { status: 'off', time: 60 }] } ], name: 'Something', description: 'jfdgljfgdfjgldfkjglfd' }]; const result = data.map(({ Chapter }) => Chapter.flatMap(({ Citems }) => Citems).reduce((a, { status, time }) => ({...a, [status]: (a[status] || 0) + time }), {}) ); console.log(result);

Answer 2

I made it using map and flatMap .

data.map(({ Chapter }) => {
  let on = 0;
  let off = 0;

  Chapter.flatMap(({ Citems }) => Citems).map((item) => {
    if (item.status === "on") {
      on += item.time;
    } else {
      off += item.time;
    }
  });

  return { on, off };
});

 const data = [ { Chapter: [ { Cname: "chapter 1", Citems: [ { status: "on", time: 30 }, { status: "on", time: 60 } ] }, { Cname: "chapter 2", Citems: [ { status: "on", time: 30 }, { status: "off", time: 60 } ] } ], name: "Something", description: "jfdgljfgdfjgldfkjglfd" }, { Chapter: [ { Cname: "chapter 1", Citems: [ { status: "on", time: 30 }, { status: "on", time: 60 } ] }, { Cname: "chapter 2", Citems: [ { status: "on", time: 30 }, { status: "off", time: 60 } ] } ], name: "Something", description: "jfdgljfgdfjgldfkjglfd" }, { Chapter: [ { Cname: "chapter 1", Citems: [ { status: "on", time: 30 }, { status: "on", time: 60 } ] }, { Cname: "chapter 2", Citems: [ { status: "on", time: 30 }, { status: "off", time: 60 } ] } ], name: "Something", description: "jfdgljfgdfjgldfkjglfd" } ]; const result = data.map(({ Chapter }) => { let on = 0; let off = 0; Chapter.flatMap(({ Citems }) => Citems).map((item) => { if (item.status === "on") { on += item.time; } else { off += item.time; } }); return { on, off }; }); console.log(result);