filter objects with same id not javascript .filter ()

Question

I need to make a filter in an array, also need to have a counter to know how many records it has as the same id. I tried to do with the filter but I did not get it because I did not know what to compare it with. it is a list of students, it has only 3 different ones, and it repeats itself several times, because it is a list of medicines that are repeated for students.

var arr = [
    {
        "gl90Tabl": null,
        "linkRece": "",
        "co01Apme": 5359,
        "co90Alun": 921,
        "co00Apme": 281,
        "dataApme": "2019-03-06",
        "horaApme": "10:00",
        "nomeApme": "Tylenol",
        "dosaApme": "10 gotas",
        "viadApme": "Oral",
        "obsApme": "Aplicar mesmo que chore.",
        "situApme": "PEND",
        "dhapApme": null
    },
    {
        "gl90Tabl": null,
        "linkRece": "",
        "co01Apme": 5360,
        "co90Alun": 921,
        "co00Apme": 281,
        "dataApme": "2019-03-06",
        "horaApme": "11:00",
        "nomeApme": "Tylenol",
        "dosaApme": "10 gotas",
        "viadApme": "Oral",
        "obsApme": "Aplicar mesmo que chore.",
        "situApme": "PEND",
        "dhapApme": null
    },
    {
        "gl90Tabl": null,
        "linkRece": "",
        "co01Apme": 5361,
        "co90Alun": 921,
        "co00Apme": 281,
        "dataApme": "2019-03-06",
        "horaApme": "12:00",
        "nomeApme": "Tylenol",
        "dosaApme": "10 gotas",
        "viadApme": "Oral",
        "obsApme": "Aplicar mesmo que chore.",
        "situApme": "PEND",
        "dhapApme": null
    },
    {
        "gl90Tabl": null,
        "linkRece": "",
        "co01Apme": 5362,
        "co90Alun": 921,
        "co00Apme": 281,
        "dataApme": "2019-03-06",
        "horaApme": "14:00",
        "nomeApme": "Tylenol",
        "dosaApme": "10 gotas",
        "viadApme": "Oral",
        "obsApme": "Aplicar mesmo que chore.",
        "situApme": "PEND",
        "dhapApme": null
    },
    {
        "gl90Tabl": null,
        "linkRece": "",
        "co01Apme": 5363,
        "co90Alun": 921,
        "co00Apme": 281,
        "dataApme": "2019-03-06",
        "horaApme": "16:00",
        "nomeApme": "Tylenol",
        "dosaApme": "10 gotas",
        "viadApme": "Oral",
        "obsApme": "Aplicar mesmo que chore.",
        "situApme": "PEND",
        "dhapApme": null
    },
    {
        "gl90Tabl": null,
        "linkRece": "",
        "co01Apme": 5340,
        "co90Alun": 2601,
        "co00Apme": 279,
        "dataApme": "2019-03-06",
        "horaApme": "16:00",
        "nomeApme": "Aspirina",
        "dosaApme": "10 Gotas",
        "viadApme": "Oral",
        "obsApme": "Aplicar mesmo que chore",
        "situApme": "PEND",
        "dhapApme": null
    },
    {
        "gl90Tabl": null,
        "linkRece": "",
        "co01Apme": 5357,
        "co90Alun": 455,
        "co00Apme": 280,
        "dataApme": "2019-03-06",
        "horaApme": "22:00",
        "nomeApme": "Dipirona",
        "dosaApme": "10ml",
        "viadApme": "Oral",
        "obsApme": "",
        "situApme": "PEND",
        "dhapApme": null
    },
    {
        "gl90Tabl": null,
        "linkRece": "",
        "co01Apme": 5358,
        "co90Alun": 455,
        "co00Apme": 280,
        "dataApme": "2019-03-06",
        "horaApme": "23:00",
        "nomeApme": "Dipirona",
        "dosaApme": "10ml",
        "viadApme": "Oral",
        "obsApme": "",
        "situApme": "PEND",
        "dhapApme": null
    }
]

console.log(arr)

Just to clarify, you're looking for all items with duplicate IDs, not just items matching a specific ID? — Kai
– Kai, Commented Mar 6, 2019 at 22:52
I don't see anything named id,.. what property is meant to be the id? — Keith
– Keith, Commented Mar 6, 2019 at 23:11
exactly, I want to join all items with the same id, and also show how many times each was repeated, the field to use with id is the co90Alun. — Taiuan Pagini
– Taiuan Pagini, Commented Mar 7, 2019 at 23:33

Morten Twellmann · Accepted Answer · 2019-03-06 23:16:00Z

1

To count the number of times some property is the same, you could loop through the array and do something like this:

let arr = [
    {
        id: 1,
        name: "Joe"
    },
    {
        id: 1,
        name: "Joe"
    },
    {
        id: 2,
        name: "Mary"
    }
];

let idCounts = {};
const propertyToCount = 'id';
for (let i = 0; i < arr.length; i++) {
    const elem = arr[i];

    if(typeof idCounts[elem[propertyToCount]] === 'undefined') {
        idCounts[elem[propertyToCount]] = 1;
    }
    else {
        idCounts[elem[propertyToCount]] = idCounts[elem[propertyToCount]] + 1;
    }
}

I hope I understood the question correctly.

answered Mar 6, 2019 at 23:16

Morten Twellmann

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