Loop through array of objects and add objects that have the same id

Question

I have an array of objects as below and I want to add the quantity of those objects whose product_id is the same.

[
      {
        "BARKOD": "Pa Detatime",
        "DETAJIM1": "",
        "DETAJIM2": "",
        "DTMODIFIKIM": "2017-10-02T16:06:53.206Z",
        "product_id": "SD13137",
        "KODI": "MX02",
        "KODNJESIA1": "cope",
        "PERSHKRIMARTIKULLI": "Emporio Armani 4097 5574 71 56",
        "cmimibaze": 0,
        "quantity": 1
      },
      {
        "BARKOD": "Pa Detatime",
        "DETAJIM1": "",
        "DETAJIM2": "",
        "DTMODIFIKIM": "2017-10-02T16:06:53.206Z",
        "product_id": "SD13137",
        "KODI": "MX03",
        "KODNJESIA1": "cope",
        "PERSHKRIMARTIKULLI": "Emporio Armani 4097 5574 71 56",
        "cmimibaze": 0,
        "quantity": 3
      },
      {
        "BARKOD": "Pa Detatime",
        "DETAJIM1": "",
        "DETAJIM2": "",
        "DTMODIFIKIM": "2017-10-02T16:06:53.206Z",
        "product_id": "SD13141",
        "KODI": "MX02",
        "KODNJESIA1": "cope",
        "PERSHKRIMARTIKULLI": "Emporio Armani 4097 5574 71 56",
        "cmimibaze": 0,
        "quantity": 1
      }
    ]

So the end array should be like below:

[
      {
        "BARKOD": "Pa Detatime",
        "DETAJIM1": "",
        "DETAJIM2": "",
        "DTMODIFIKIM": "2017-10-02T16:06:53.206Z",
        "product_id": "SD13137",
        "KODI": "MX02",
        "KODNJESIA1": "cope",
        "PERSHKRIMARTIKULLI": "Emporio Armani 4097 5574 71 56",
        "cmimibaze": 0,
        "quantity": 4
      },
      {
        "BARKOD": "Pa Detatime",
        "DETAJIM1": "",
        "DETAJIM2": "",
        "DTMODIFIKIM": "2017-10-02T16:06:53.206Z",
        "product_id": "SD13141",
        "KODI": "MX02",
        "KODNJESIA1": "cope",
        "PERSHKRIMARTIKULLI": "Emporio Armani 4097 5574 71 56",
        "cmimibaze": 0,
        "quantity": 1
      }
    ]

I asked this question along with another one here but was able to solve only the other question. If anyone might solve I'd be very grateful. Thank you.

Answer 1

You could use reduce, like this:

 let input = [{"BARKOD": "Pa Detatime","DETAJIM1": "","ETAJIM2": "","DTMODIFIKIM": "2017-10-02T16:06:53.206Z","product_id": "SD13137","KODI": "MX02","KODNJESIA1": "cope","PERSHKRIMARTIKULLI": "Emporio Armani 4097 5574 71 56","cmimibaze": 0,"quantity": 1},{"BARKOD": "Pa Detatime","DETAJIM1": "","DETAJIM2": "","DTMODIFIKIM": "2017-10-02T16:06:53.206Z","product_id": "SD13137","KODI": "MX03","KODNJESIA1": "cope","PERSHKRIMARTIKULLI": "Emporio Armani 4097 5574 71 56","cmimibaze": 0,"quantity": 3},{"BARKOD": "Pa Detatime","DETAJIM1": "","DETAJIM2": "","DTMODIFIKIM": "2017-10-02T16:06:53.206Z","product_id": "SD13141","KODI": "MX02","KODNJESIA1": "cope","PERSHKRIMARTIKULLI": "Emporio Armani 4097 5574 71 56","cmimibaze": 0,"quantity": 1}]; let output = input.reduce(function(res, el) { if(res[el.product_id]) { res[el.product_id].quantity += el.quantity; } else { res[el.product_id] = el; } return res; }, {}); let outputArr = Object.values(output); console.log(outputArr);

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Answer 2

 var data = [{"BARKOD": "Pa Detatime", "DETAJIM1": "", "DETAJIM2": "", "DTMODIFIKIM": "2017-10-02T16:06:53.206Z", "product_id": "SD13137", "KODI": "MX02", "KODNJESIA1": "cope", "PERSHKRIMARTIKULLI": "Emporio Armani 4097 5574 71 56", "cmimibaze": 0, "quantity": 1 }, {"BARKOD": "Pa Detatime", "DETAJIM1": "", "DETAJIM2": "", "DTMODIFIKIM": "2017-10-02T16:06:53.206Z", "product_id": "SD13137", "KODI": "MX03", "KODNJESIA1": "cope", "PERSHKRIMARTIKULLI": "Emporio Armani 4097 5574 71 56", "cmimibaze": 0, "quantity": 3 }, {"BARKOD": "Pa Detatime", "DETAJIM1": "", "DETAJIM2": "", "DTMODIFIKIM": "2017-10-02T16:06:53.206Z", "product_id": "SD13141", "KODI": "MX02", "KODNJESIA1": "cope", "PERSHKRIMARTIKULLI": "Emporio Armani 4097 5574 71 56", "cmimibaze": 0, "quantity": 1 } ] var mapObj = {}; for(var a of data){ if(mapObj[a["product_id"]]== undefined) mapObj[a["product_id"]] = 0; mapObj[a["product_id"]] += a["quantity"] } var data2 = []; for(var a of data){ if(mapObj[a["product_id"]] == undefined) continue; a["quantity"] = mapObj[a["product_id"]]; data2.push(a) delete mapObj[a["product_id"]]; } console.log(data2)