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Javascript – How to change multiple array becomes array with object?

I try to use forEach and push a new array to achieve it, but the result is wrong.

const dummyArray = [
  [45292, 1, 2],
  [46292, 5, 6],
  [47292, 9, 10],
]

const resultArray: any[] = []

dummyArray.forEach((elementValue, index) => {
  resultArray.push({ date: '', price: '', code: '' })

  elementValue.forEach(value => {
    if (index === 0) {
      resultArray[index] = { ...resultArray[index], date: value }
    }
    if (index === 1) {
      resultArray[index] = { ...resultArray[index], price: value }
    }
    if (index === 2) {
      resultArray[index] = { ...resultArray[index], code: value }
    }
  })
})

console.log('resultArray', resultArray)

the result becomes

[
  { date: 2, price: '', code: ''},
  { date: '', price: 6, code: ''},
  { date: '', price: '', code: 10},
]

I want it becomes like

[
  { date: 45292, price: 1, code: 2},
  { date: 46292, price: 5, code: 6},
  { date: 47292, price: 9, code: 10},
]

How do I achieve it ?

Tags:

3

Answers


  1. 0 
        const dummyArray = [
      [45292, 1, 2],
      [46292, 5, 6],
      [47292, 9],
    ]
    
    const resultArray = []
    
    dummyArray.forEach((elementValue, index) => {
      resultArray.push({ date: elementValue[0]??'', price: elementValue[1]??'', code: elementValue[2]??'' })
    })
    console.log(resultArray)
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  2. 0

    You need a different index for your if condition (subIndex):

    dummyArray.forEach((elementValue, index) => {
  resultArray.push({ date: "", price: "", code: "" });

  elementValue.forEach((value, subIndex) => {
    if (subIndex === 0) {
      resultArray[index] = { ...resultArray[index], date: value };
    }
    if (subIndex === 1) {
      resultArray[index] = { ...resultArray[index], price: value };
    }
    if (subIndex === 2) {
      resultArray[index] = { ...resultArray[index], code: value };
    }
  });
});

    You could also do below.

    const keyArray = ["date", "price", "code"];

dummyArray.forEach((elementValue, index) => {
  elementValue.forEach((value, subIndex) => {
    resultArray[index] = { ...resultArray[index], [keyArray[subIndex]]: value };
  });
});

    Or:

    const dummyArray = [
  [45292, 1, 2],
  [46292, 5, 6],
  [47292, 9, 10],
];
const keyArray = ["date", "price", "code"];

const resultArray = dummyArray.map((elementValue) =>
  elementValue.reduce((acc, value, subIndex) => {
    return { ...acc, [keyArray[subIndex]]: value };
  }, {})
);

console.log("resultArray", resultArray);

    Note that, using reduce should come with a return inside reduce.

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  3. 0

    By far the simplest way to do this is with this one-liner – just map the dummyArray items to an object

    It also uses modern patterns like destructuring and object shorthand

    const dummyArray = [
  [45292, 1, 2],
  [46292, 5, 6],
  [47292, 9, 10],
]
const result = dummyArray.map(([date, price, code]) => ({date, price, code}))
console.log(result);
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