compare two object array and push if not exist

Question

i have bellow two object arrays

var array_1 = [{"Date": "2020-04-01", "Item" : 001},{"Date": "2020-04-03", "Item" : 002}]
var base_array = [{"Date": "2020-04-01", "Item" : null}, {"Date": "2020-04-02", "Item" : null}, 
                  {"Date": "2020-04-04", "Item" : null}]

i planning modify array_1 as bellow

 var array_1 = [{"Date": "2020-04-01", "Item" : 001},
                {"Date": "2020-04-02", "Item" : null},
                {"Date": "2020-04-03", "Item" : 002},
                {"Date": "2020-04-04", "Item" : null}]

since date "2020-04-02" and "2020-04-04" not exist in array_1, those dates should be push with "item" null and "2020-04-01" should not be push since its already exist in array_1.

i've tried make following each loop but not able to continue

small note : base_array will always contain more value than array_1. so that why i used base_array as my initial loop

$.each(base_array , function (key,bvalue) {

    $.each(array_1, function (key,value) {
          if(bvalue.Date != value.Date){

               array_1.push({"Date" : value.Date, "Item": value.Item})
          }
    })
})

Nick · Accepted Answer · 2020-04-03 06:43:56Z

2

You can use Array.reduce() on base_array, passing array_1 as the initial value and only adding values from base_array where the Date does not already exist in the carry value:

var array_1 = [{
  "Date": "2020-04-01",
  "Item": 001
}, {
  "Date": "2020-04-03",
  "Item": 002
}];
var base_array = [{
    "Date": "2020-04-01",
    "Item": null
  }, {
    "Date": "2020-04-02",
    "Item": null
  },
  {
    "Date": "2020-04-04",
    "Item": null
  }
];

array_1 = base_array.reduce((c, v) => c.concat(c.some(e => e.Date == v.Date) ? [] : [v]), array_1);
console.log(array_1);

answered Apr 3, 2020 at 6:43

Nick

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Nina Scholz · Accepted Answer · 2020-04-03 06:49:16Z

2

You could take a hash table, assign the object to the same date and get an array of objects.

At the end sort the array by Date.

var array_1 = [{ Date: "2020-04-01", Item: "001" }, { Date: "2020-04-03", Item: "002" }],
    base_array = [{ Date: "2020-04-01", Item: null }, { Date: "2020-04-02", Item: null }, { Date: "2020-04-04", Item: null }],
    result = Object
        .values([...base_array, ...array_1].reduce((r, o) => (r[o.Date] = o, r), {}))
        .sort(({ Date: a }, { Date: b }) => a > b || -(a < b))

console.log(result);

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answered Apr 3, 2020 at 6:49

Nina Scholz

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jonathanGB · Accepted Answer · 2020-04-03 06:46:41Z

1

I'm not sure if the order mattered to you, but if not here's one solution

// Keep track of all dates already present in `array_1`.
let array_1_dates = new Set(array_1.map(array_1_elem => array_1_elem.Date));

// Push elements from `base_array` that are not in `array_1`.
for (let base_array_elem of base_array) {
  if (!array_1_dates.has(base_array_elem.Date)) {
    array_1.push(base_array_elem);
  }
}

answered Apr 3, 2020 at 6:46

jonathanGB

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Comments

ariel · Accepted Answer · 2020-04-03 06:54:56Z

1

First remove from base_array the itens that already are on array_1, using filter. Then concat.

var array_1 = [{"Date": "2020-04-01", "Item" : 001},{"Date": "2020-04-03", "Item" : 002}]
var base_array = [{"Date": "2020-04-01", "Item" : null}, {"Date": "2020-04-02", "Item" : null}, {"Date": "2020-04-04", "Item" : null}]
                  
var filtered = base_array.filter(({Date}) => !array_1.some(el => el.Date == Date));
var result = array_1.concat(filtered);
console.log(result);

edited Apr 3, 2020 at 6:54

answered Apr 3, 2020 at 6:37

ariel

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Comments

Pranav C Balan · Accepted Answer · 2020-04-05 13:45:49Z

You can use a simple loop and find the insert position using comparison.

var array_1 = [{
  "Date": "2020-04-01",
  "Item": 001
}, {
  "Date": "2020-04-03",
  "Item": 002
}]
var base_array = [{
    "Date": "2020-04-01",
    "Item": null
  }, {
    "Date": "2020-04-02",
    "Item": null
  },
  {
    "Date": "2020-04-04",
    "Item": null
  }
]

// iterate over second array
base_array.forEach(el => {
  for (let i = 0; i < array_1.length; i++) {
    // if value found return
    if (array_1[i].Date === el.Date) return;
    // if position found, insert and return
    if (array_1[i].Date > el.Date) {
      array_1.splice(i, 0, el);
      return
    }
  }
  // or insert at the end of the array
  array_1.push(el);
})

console.log(array_1);

NOTE : Assuming the first array is always in sorted order.

UPDATE : Or if order may change and you don't want to add them at the end then you can use Array#some and Array#filter method.

var array_1 = [{
  "Date": "2020-04-01",
  "Item": 001
}, {
  "Date": "2020-04-03",
  "Item": 002
}]
var base_array = [{
    "Date": "2020-04-01",
    "Item": null
  }, {
    "Date": "2020-04-02",
    "Item": null
  },
  {
    "Date": "2020-04-04",
    "Item": null
  }
]

array_1.push(...base_array.filter(o => array_1.every(o1 => o1.Date !== o.Date)))

console.log(array_1);

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