Missing dates to add in a json object of keys

Question

I have two arrays one with constant dates and other with multiple JSON objects of dates, but the JSON objects have some missing dates how to add the missing dates from constant dates array to the second array of JSON objects

constantdates =  [
    'Jul 7', 
    'Jul 8',
    'Jul 9', 
    'Jul 10',
    'Jul 27', 
    'Jul 16',
    'Jul 30', 
    'Jul 26',
    'Jul 12', 
    'Jul 22',
    'Jul 17',
    'Jul 24',
    'Jul 19', 
    'Jul 14',
    'Jul 25', 
    'Jul 13',
    'Jul 23', 
    'Jul 15',
    'Jul 29', 
    'Jul 11',
    'Jul 28', 
    'Jul 21',
    'Jul 20', 
    'Jul 18'
  ]

myarray = [{
    name: 'Arun',
    address: 'hydrabad',
    worker: 'test',
    'Jul 11': 1425,
    'Jul 15': 1425,
    'Jul 16': 1475,
    'Jul 17': 1425,
    'Jul 21': 1475,
    'Jul 22': 1425,
    'Jul 23': 1475,
    'Jul 24': 1225,
    'Jul 25': 1425,
    'Jul 26': 1075,
    'Jul 27': 1475,
    'Jul 29': 1425,
    'Jul 30': 1325,
  },
  {
    name: 'Abi',
    address: 'delhi',
    worker: 'test',
    'Jul 11': 1425,
    'Jul 12': 1275,
    'Jul 13': 1475,
    'Jul 14': 1275,
    'Jul 15': 1425,
    'Jul 16': 1475,
    'Jul 17': 1425,
    'Jul 18': 1425,
    'Jul 19': 1475,
    'Jul 21': 1475,
    'Jul 22': 1425,
    'Jul 23': 1475,
    'Jul 24': 1225,
    'Jul 25': 1425,
    'Jul 26': 1075,
    'Jul 27': 1475,
    'Jul 29': 1425,
    'Jul 30': 1325
  }]

Expected Output

 [{
    name: 'Arun',
    address: 'hydrabad',
    worker: 'test',
    'Jul 7': null, 
    'Jul 8': null,
    'Jul 9': null, 
    'Jul 10': null,
    'Jul 11': 1425,
    'Jul 12': null,
    'Jul 13': null,
    'Jul 14': null,
    'Jul 15': 1425,
    'Jul 16': 1475,
    'Jul 17': 1425,
    'Jul 18': null,
    'Jul 19': null,
    'Jul 20': null,
    'Jul 21': 1475,
    'Jul 22': 1425,
    'Jul 23': 1475,
    'Jul 24': 1225,
    'Jul 25': 1425,
    'Jul 26': 1075,
    'Jul 27': 1475,
    'Jul 28': null,
    'Jul 29': 1425,
    'Jul 30': 1325,
  },
  {
    name: 'Abi',
    address: 'delhi',
    worker: 'test',
    'Jul 7': null, 
    'Jul 8': null,
    'Jul 9': null, 
    'Jul 10': null,
    'Jul 11': 1425,
    'Jul 12': 1275,
    'Jul 13': 1475,
    'Jul 14': 1275,
    'Jul 15': 1425,
    'Jul 16': 1475,
    'Jul 17': 1425,
    'Jul 18': 1425,
    'Jul 19': 1475,
    'Jul 20': null,
    'Jul 21': 1475,
    'Jul 22': 1425,
    'Jul 23': 1475,
    'Jul 24': 1225,
    'Jul 25': 1425,
    'Jul 26': 1075,
    'Jul 27': 1475,
    'Jul 28': null,
    'Jul 29': 1425,
    'Jul 30': 1325
  }]

Answer 1

Use reduce . Inside reduce callback use forEach on the dates array. Inside forEach callback take each element from dates array and check if same element exist in the object of myArray. If it does not exist then add it as a new key and set value to null.

 const dates = [ 'Jul 7', 'Jul 8', 'Jul 9', 'Jul 10', 'Jul 27', 'Jul 16', 'Jul 30', 'Jul 26', 'Jul 12', 'Jul 22', 'Jul 17', 'Jul 24', 'Jul 19', 'Jul 14', 'Jul 25', 'Jul 13', 'Jul 23', 'Jul 15', 'Jul 29', 'Jul 11', 'Jul 28', 'Jul 21', 'Jul 20', 'Jul 18' ] const myarray = [{ name: 'Arun', address: 'hydrabad', worker: 'test', 'Jul 11': 1425, 'Jul 15': 1425, 'Jul 16': 1475, 'Jul 17': 1425, 'Jul 21': 1475, 'Jul 22': 1425, 'Jul 23': 1475, 'Jul 24': 1225, 'Jul 25': 1425, 'Jul 26': 1075, 'Jul 27': 1475, 'Jul 29': 1425, 'Jul 30': 1325, }, { name: 'Abi', address: 'delhi', worker: 'test', 'Jul 11': 1425, 'Jul 12': 1275, 'Jul 13': 1475, 'Jul 14': 1275, 'Jul 15': 1425, 'Jul 16': 1475, 'Jul 17': 1425, 'Jul 18': 1425, 'Jul 19': 1475, 'Jul 21': 1475, 'Jul 22': 1425, 'Jul 23': 1475, 'Jul 24': 1225, 'Jul 25': 1425, 'Jul 26': 1075, 'Jul 27': 1475, 'Jul 29': 1425, 'Jul 30': 1325 } ] const newData = myarray.reduce((acc, curr) => { let obj = {} obj['fullName'] = curr.name; obj['address'] = curr.address; obj['worker'] = curr.worker; dates.forEach((item) => { if (curr.hasOwnProperty(item)) { obj[item] = curr[item] } else { obj[item] = null } }) acc.push(obj) return acc; }, []); console.log(newData)

Answer 2

Using no dependencies, and one line:

myarray = myarray.map(w => Object.assign(constantdates.reduce((a, b) => (a[b] = null, a), {}), w))

The reduction takes the array of dates and makes it like { 'Date': null }, and then we use Object.assign to copy the original value onto those keys.