How to recalculate an array of object from nested objects?-CodePudding

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

CodePudding user response：

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);

CodePudding user response：

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);