How to convert the given object with objects to an array with objects

osagognitive's solution has a few drawbacks, in my opinion:

• it does not filter out the timestamps, creating a weird { currency: "timestamp" } element
• it accesses the global data object in ...data[key] when constructing the records. Replacing Object.keys() with Object.entries() would avoid this.

Besides, you can very well define functions instead of abstruse lambdas. Obfuscated JavaScript won't run any faster, but you'll spend a lot more time debugging it, not to mention some else trying to make sense of it.

For instance:

function ConvertToCurrencyArray (data) {

  function SelectCurrency ([key, record]) { return key.length == 3 }

  function FormatRecord ([key, record]) { return { currency: key, ...record } }

  return Object.entries(data).filter(SelectCurrency).map(FormatRecord);
}

If something goes wrong, you can easily add debug traces:

function ConvertToCurrencyArray (data) {

  function SelectCurrency ([key, record]) {
    if (key.length != 3) console.log ("filtering out " + key);
    return key.length == 3
  }

  function FormatRecord ([key, record]) {
    if (Object.keys(record).length != 3) // 3 fields expected
      console.log ("unexpected record " + key + ": " + JSON.stringify(record));

    return { currency: key, ...record }
  }

  return Object.entries(data).filter(SelectCurrency).map(FormatRecord);
}

Example:

ConvertToCurrencyArray( { "USD": { "7d": "32053.72", "30d": "33194.68", "24h": "31370.42" }, "AUD": { "7d": "43134.11", "30d": "44219.00", "24h": "42701.11" }, "RUB": { "7d": "2451451.45", "30d": "2465896.74", "24h": "2398589.80" }, "timestamp": 1626699964, "JPY": { "7d": "3537735.55", "30d": "3664620.47", "24h": "3472632.46" }, "BRL": { "7d": "167555.18", "30d": "169473.27", "24h": "163054.93" }, "ILS": { "7d": "108658.72", "30d": "111663.67", "24h": "106988.58" }, "GBP": { "7d": "23257.66", "30d": "23838.55" }, "PLNZ": { "7d": "124869.61", "30d": "127872.57", "24h": "122668.16" }, "CAD": { "7d": "40425.62", "30d": "41444.76", "24h": "39827.13" }, "EUR": { "7d": "27187.74", "30d": "27955.81", "24h": "26659.79" } })

Output:

filtering out timestamp
filtering out PLNZ
unexpected record GBP: {"7d":"23257.66","30d":"23838.55"}

Now if you're absolutely sure that

• your input data are 100% reliable and you can read them without any sanity check
• you won't ever need to rethink your output format
• you won't touch this code ever again

you can use this instead:

var arrayOfCurrencies = 
  Object.entries(data)
        .filter(([key, record]) => key.length == 3)
        .map   (([key, record]) => ({ currency: key, ...record }))

Could you try like below

const json = '{"result":true, "count":42}';
const obj = JSON.parse(json);