how to change keys of array

Question

I have the following array of objects. How do I change the keys of the array (0,1) to the skipperid (217,1)

[0:
        {
            "type": "RES",
            "date": "2022-05-14",
            "doy": 133,
            "skipperid": 217,
            "boat": "Laura",
            "start": "09:00:00",
            "end": "22:00:00",
            "spots": 5,
            "fname": "David",
            "lname": "Cross"
        }, 
     1:{
            "type": "SAIL",
            "date": "2022-05-14",
            "doy": 133,
            "skipperid": 1,
            "boat": "Avrora",
            "start": "10:00:00",
            "end": "13:00:00",
            "spots": 3,
            "fname": "Bob",
            "lname": "Smith"
        }
    ]

array keys are indexes, are you saying you want to move the item at index 0 to index 217? — knicholas
– knicholas, Commented Feb 3, 2022 at 20:07
If you want to use the skipperid as the key, you'd need to copy everything into an Object. — mykaf
– mykaf, Commented Feb 3, 2022 at 20:08

Kinglish · Accepted Answer · 2022-02-03 20:10:32Z

2

Javascript arrays always have numeric indexes. If you want to have keys, you'll need to convert into an object as shown here.

let data = [{
    "type": "RES",
    "date": "2022-05-14",
    "doy": 133,
    "skipperid": 217,
    "boat": "Laura",
    "start": "09:00:00",
    "end": "22:00:00",
    "spots": 5,
    "fname": "David",
    "lname": "Cross"
  },
  {
    "type": "SAIL",
    "date": "2022-05-14",
    "doy": 133,
    "skipperid": 1,
    "boat": "Avrora",
    "start": "10:00:00",
    "end": "13:00:00",
    "spots": 3,
    "fname": "Bob",
    "lname": "Smith"
  }
]

data = data.reduce((b,a) => ({...b, [a.skipperid]:a}), {});
console.log(data['217'])

answered Feb 3, 2022 at 20:10

Kinglish

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Comments

knicholas · Accepted Answer · 2022-02-03 20:26:51Z

0

I definitely suggest using an object like @Kinglish example.

Moving the position from current index to index by skipperid creates an array of size (highest skipperid), leaving all index != skipperid as undefined

USE AN OBJECT

This is messy:

let data = [{
    "type": "RES",
    "date": "2022-05-14",
    "doy": 133,
    "skipperid": 217,
    "boat": "Laura",
    "start": "09:00:00",
    "end": "22:00:00",
    "spots": 5,
    "fname": "David",
    "lname": "Cross"
  },
  {
    "type": "SAIL",
    "date": "2022-05-14",
    "doy": 133,
    "skipperid": 1,
    "boat": "Avrora",
    "start": "10:00:00",
    "end": "13:00:00",
    "spots": 3,
    "fname": "Bob",
    "lname": "Smith"
  }
]
data.forEach((o,i,self)=> {
if(o?.skipperid != i){
self[o.skipperid] = o;
self[i] = undefined
}
})
console.log(data)

answered Feb 3, 2022 at 20:26

knicholas

5304 silver badges10 bronze badges

2 Comments

DCR Over a year ago

I don’t think you are correct. Keys are just strings. Having a key of 0 and another key of 217 does not create an object of 218 keys where 216 are undefined

knicholas Over a year ago

it doesn't create an object, it creates an array. For example, if you run array=[]; array[217]="Something"; console.log(array); you will get an array of 218 indexes where 216 are undefined and index 217 being 'Something'

Rohìt Jíndal · Accepted Answer · 2022-02-04 10:09:40Z

Observations :

JSON you provided is not a valid JSON.
result will be an object instead of an array.

Working Demo :

const arr = [{
        "type": "RES",
        "date": "2022-05-14",
        "doy": 133,
        "skipperid": 217,
        "boat": "Laura",
        "start": "09:00:00",
        "end": "22:00:00",
        "spots": 5,
        "fname": "David",
        "lname": "Cross"
    },
    {
        "type": "SAIL",
        "date": "2022-05-14",
        "doy": 133,
        "skipperid": 1,
        "boat": "Avrora",
        "start": "10:00:00",
        "end": "13:00:00",
        "spots": 3,
        "fname": "Bob",
        "lname": "Smith"
    }
];

const obj = {};

arr.forEach((item) => {
    obj[item.skipperid] = item
});

console.log(obj)

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