How should I slice the array of objects of objects

Question

i have a array which looks like this :

[

{
    "1": {
        "id": 1,
        "price": 569.2,
        "marketcap": 94943213384.68,
        "timestamp": 1637136047,
        "datetime": "2021-11-17 08:00:47"
    },
    "2": {
        "id": 2,
        "price": 59745.7,
        "marketcap": 1127634159487.02,
        "timestamp": 1637136064,
        "datetime": "2021-11-17 08:01:04"
    },
    "3": {
        "id": 3,
        "price": 592.53,
        "marketcap": 11199494644.95126,
        "timestamp": 1637136053,
        "datetime": "2021-11-17 08:00:53"
    }
},
{
    "1": {
        "id": 1,
        "last30dcommits": null,
        "activity": "No Github Repo Found"
    },
    "2": {
        "id": 2,
        "last30dcommits": 109,
        "activity": "High Activity"
    },
    "3": {
        "id": 3,
        "last30dcommits": 44,
        "activity": "Medium Activity"
    }
},
{
    "1": {
        "id": 1,
        "change24h": -6.75,
        "change7d": -10.18,
        "change30d": 17.32,
        "timestamp24h": 1637035200,
        "timestamp7d": 1636516800,
        "timestamp30d": 1634529600
    },
    "2": {
        "id": 2,
        "change24h": -3.22,
        "change7d": -12.58,
        "change30d": -5.17,
        "timestamp24h": 1637035200,
        "timestamp7d": 1636516800,
        "timestamp30d": 1634529600
    },
    "3": {
        "id": 3,
        "change24h": -6.37,
        "change7d": -17.81,
        "change30d": -5.04,
        "timestamp24h": 1637035200,
        "timestamp7d": 1636516800,
        "timestamp30d": 1634529600
    }
},
{
    "1": {
        "tweetsRating": 44.04,
        "newsRating": 38.42
    },
    "2": {
        "tweetsRating": 14.76,
        "newsRating": -1.27
    },
    "3": {
        "tweetsRating": 0,
        "newsRating": 44.35
    } 
},
]

I am implementing a pagination in the front end in which I am slicing each objects in each object in the array to a given value so that I get a result something like this if I slice (0,2)

[

{
    "1": {
        "id": 1,
        "price": 569.2,
        "marketcap": 94943213384.68,
        "timestamp": 1637136047,
        "datetime": "2021-11-17 08:00:47"
    },
    "2": {
        "id": 2,
        "price": 59745.7,
        "marketcap": 1127634159487.02,
        "timestamp": 1637136064,
        "datetime": "2021-11-17 08:01:04"
    }
},
{
    "1": {
        "id": 1,
        "last30dcommits": null,
        "activity": "No Github Repo Found"
    },
    "2": {
        "id": 2,
        "last30dcommits": 109,
        "activity": "High Activity"
    }
},
{
    "1": {
        "id": 1,
        "change24h": -6.75,
        "change7d": -10.18,
        "change30d": 17.32,
        "timestamp24h": 1637035200,
        "timestamp7d": 1636516800,
        "timestamp30d": 1634529600
    },
    "2": {
        "id": 2,
        "change24h": -3.22,
        "change7d": -12.58,
        "change30d": -5.17,
        "timestamp24h": 1637035200,
        "timestamp7d": 1636516800,
        "timestamp30d": 1634529600
    }
},
{
    "1": {
        "tweetsRating": 44.04,
        "newsRating": 38.42
    },
    "2": {
        "tweetsRating": 14.76,
        "newsRating": -1.27
    }
},
]

means only 2 objects should be sliced out. my function is as following but its not working.

const sliceData = (array,start,end)=>{
    array.forEach(arr=>{
       Object.keys(arr).slice(start - 1, end + 1).reduce((result, key) => {
          result[key] = arr[key];

      return result;
    }
})
}

Here start and end represents the index of starting object in a page and index of last object in the page respectively. Can anyone help me with the code? I'll be very grateful.

Nina Scholz · Accepted Answer · 2021-11-17 09:59:44Z

2

You could slice the entries for new objects.

const
    data = [{ "1": { id: 1, price: 569.2, marketcap: 94943213384.68, timestamp: 1637136047, datetime: "2021-11-17 08:00:47" }, "2": { id: 2, price: 59745.7, marketcap: 1127634159487.02, timestamp: 1637136064, datetime: "2021-11-17 08:01:04" }, "3": { id: 3, price: 592.53, marketcap: 11199494644.95126, timestamp: 1637136053, datetime: "2021-11-17 08:00:53" } }, { "1": { id: 1, last30dcommits: null, activity: "No Github Repo Found" }, "2": { id: 2, last30dcommits: 109, activity: "High Activity" }, "3": { id: 3, last30dcommits: 44, activity: "Medium Activity" } }, { "1": { id: 1, change24h: -6.75, change7d: -10.18, change30d: 17.32, timestamp24h: 1637035200, timestamp7d: 1636516800, timestamp30d: 1634529600 }, "2": { id: 2, change24h: -3.22, change7d: -12.58, change30d: -5.17, timestamp24h: 1637035200, timestamp7d: 1636516800, timestamp30d: 1634529600 }, "3": { id: 3, change24h: -6.37, change7d: -17.81, change30d: -5.04, timestamp24h: 1637035200, timestamp7d: 1636516800, timestamp30d: 1634529600 } }, { "1": { tweetsRating: 44.04, newsRating: 38.42 }, "2": { tweetsRating: 14.76, newsRating: -1.27 }, "3": { tweetsRating: 0, newsRating: 44.35 } }],
    result = data.map(o => Object.fromEntries(Object.entries(o).slice(0, 2)));

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

answered Nov 17, 2021 at 9:59

Nina Scholz

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1 Comment

rex Over a year ago

This is awesome but what if objects keys are not in the ascending order. What if first object has inner object with "3" key first. Then we will have the object with key "3" in the output. However, Not sure if that is the actual requirement.

rex · Accepted Answer · 2021-11-17 10:10:16Z

1

I really think the data format/structure sent from BackEnd should be changed. Instead of sending Array of objects you should consider sending Array of Array of objects from Backend. This is because essentially the id of the object is key. However, Here is how you can slice the data if you do not have permission to change data sent from Backend.

const sliceData = (array,start,end)=>{ 
    return array.map(el => {
        let newObj = Object.values(el).filter(x => x.id>start && x.id<=end).reduce((acc,x) => {
          acc[x.id] = x;
          return acc;  
        } ,{}) 
        return newObj;
    });
}

answered Nov 17, 2021 at 10:10

rex

3591 silver badge5 bronze badges

2 Comments

Vedant Singh Over a year ago

Thanks ..made some changes and its working properly.

rex Over a year ago

You are most welcome. If it worked for you, you can mark this as accepted answer. thanks

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