javascript中的数组数组到对象数组的数组

Question

I would like to convert my array of array of objects to array of objects.

I would like to merge two data into one. I have a data holder which is an array

const dataholder = ["itemCode","item","cashier"];

and a data that needs to map in dataholder key

const record = [
        {
          itemCode: { value: 1},
          item: { value: 'Pen'},
          cashier: {value: 'Sam'}
        },
        [
          itemCode: {value: 2},
          item: {value: 'Eraser'},
          cashier: {value: 'Kim'}
        ]
    ];

I have tried this code below but it the result turns to array of array of array

record?.map( item => {
        return dataholder ?.map( (field) => {
            return {
                [field]: item[field]?.value
            }
        })
    })

and here's the output

       [
        [
          {'itemCode': 1},
          {'item': 'Pen'},
          {'cashier': 'Sam'}
        ],
        [
          {'itemCode': 2},
          {'item': 'Eraser'},
          {'cashier': 'Kim'}
        ]
]

expected result

[
        {
            itemCode: 1,
            item: 'Pen',
            cashier: 'Sam'
        },
        {
            itemCode: 2,
            item: 'Eraser',
            cashier: 'Kim'
        }
    ]

Thanks for the help in advance!

Answer 1

Try this:

record?.map(item => {
  const obj = {}
  for (const key in item)
      if (dataholder.includes(key))
        obj[key] = item[key].value
  return obj
})

Answer 2

You can .map() over your record objects, and for each object, map over your dataholder array to create an array of [key, obj[key].value] arrays. This will result in your inner .map() creating an array of the form...

[[key, value], [key2, value2], ...]

... for each object ( obj ) that is iterated on by your outer .map() , where the value is obtained from the obj . You can then use Object.fromEntries() to convert this array of key-value pair entries into an object:

 const dataholder = ["itemCode","item","cashier"]; const record = [ { itemCode: { value: 1}, item: { value: 'Pen'}, cashier: {value: 'Sam'} }, { itemCode: {value: 2}, item: {value: 'Eraser'}, cashier: {value: 'Kim'} } ]; const res = record.map(obj => Object.fromEntries( dataholder.map(key => [key, obj[key].value]) )); console.log(res);

Answer 3

Instead, in the inner loop, you could use reduce

const res = record.map((item) => {
  return dataholder.reduce((acc, field) => {
    return {
      ...acc,
      [field]: item[field].value,
    };
  }, {});
});

 const dataholder = ["itemCode", "item", "cashier"]; const record = [ { itemCode: { value: 1 }, item: { value: "Pen" }, cashier: { value: "Sam" }, }, { itemCode: { value: 2 }, item: { value: "Eraser" }, cashier: { value: "Kim" }, }, ]; const res = record.map((item) => { return dataholder.reduce((acc, field) => { return {...acc, [field]: item[field].value, }; }, {}); }); console.log(res);

Answer 4

You can try this way (using .map combines with for... of )

var result = record.map(r => {
  var item = {};
  for(let key of dataholder)  item[key] = r[key].value;
  return item;
});

 var dataholder = ["itemCode","item","cashier"]; var record = [ { itemCode: { value: 1}, item: { value: 'Pen'}, cashier: {value: 'Sam'} }, { itemCode: {value: 2}, item: {value: 'Eraser'}, cashier: {value: 'Kim'} } ]; var result = record.map(r => { var item = {}; for(let key of dataholder) item[key] = r[key].value; return item; }); console.log(result);