Remove specific array element from JSON object in javascript

Question

I have below array of Objects-

var myarray = [ { "id": "", "AlphaNumber": "ADF12345", "terms": "1" }, { "id": "ABC12345", "AlphaNumber": "LL8888", "terms": "1" }, { "id": "", "AlphaNumber": "KK6666", "terms": "2" }, { "id": "", "AlphaNumber": "QQ1111", "terms": "3" }, { "id": "ABC12346", "AlphaNumber": "RR4444", "terms": "3" }, { "id": "", "AlphaNumber": "SS1111", "terms": "5" }, { "id": "ABC12347", "AlphaNumber": "ASQE223", "terms": "5" } ]

I want to check if multiple entries for the same terms are present in the array and remove the node that has id="" which means my output would have an entry having term and id not equals ''(empty string) for duplicate term entries.

Final value of myarray after the logic could be as below:

[{"id":"ABC12345","AlphaNumber":"LL8888","terms":"1"},{"id":"","AlphaNumber":"KK6666","terms":"2"},{"id":"ABC12346","AlphaNumber":"RR4444","terms":"3"},{"id":"ABC12347","AlphaNumber":"ASQE223","terms":"5"}]

adiga · Accepted Answer · 2021-04-24 12:16:22Z

2

Create a map object with terms as key. If the current terms doesn't exist in map or the already existing object doesn't have id, use the current object

const myarray = [ { "id": "", "AlphaNumber": "ADF12345", "terms": "1" }, { "id": "ABC12345", "AlphaNumber": "LL8888", "terms": "1" }, { "id": "", "AlphaNumber": "KK6666", "terms": "2" }, { "id": "", "AlphaNumber": "QQ1111", "terms": "3" }, { "id": "ABC12346", "AlphaNumber": "RR4444", "terms": "3" }, { "id": "", "AlphaNumber": "SS1111", "terms": "5" }, { "id": "ABC12347", "AlphaNumber": "ASQE223", "terms": "5" } ]

const map = {};

for (const o of myarray) {
  if (!map[o.terms]?.id)
    map[o.terms] = o
}

console.log( Object.values(map) )

edited Apr 24, 2021 at 12:16

answered Apr 24, 2021 at 12:04

adiga

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Nguyễn Văn Phong · Accepted Answer · 2022-03-12 08:04:31Z

1

Using `Array#reduce` and `Map`

Group your data by terms in a Map.
Find an item where id is not an empty string, if such an item does not exist pick the first item.

const 
  myarray = [ { "id": "", "AlphaNumber": "ADF12345", "terms": "1" }, { "id": "ABC12345", "AlphaNumber": "LL8888", "terms": "1" }, { "id": "", "AlphaNumber": "KK6666", "terms": "2" }, { "id": "", "AlphaNumber": "QQ1111", "terms": "3" }, { "id": "ABC12346", "AlphaNumber": "RR4444", "terms": "3" }, { "id": "", "AlphaNumber": "SS1111", "terms": "5" }, { "id": "ABC12347", "AlphaNumber": "ASQE223", "terms": "5" } ],
  
  res = Array.from(myarray.reduce(
    (m, o) => (m.has(o.terms) ? m.get(o.terms).push(o) : m.set(o.terms, [o]), m),
    new Map()
  ).values(), (v) => v.find(o => o.id !== "") || v[0]);

console.log(JSON.stringify(res));

edited Mar 12, 2022 at 8:04

Nguyễn Văn Phong

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answered Apr 24, 2021 at 12:04

Som Shekhar Mukherjee

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Nguyễn Văn Phong · Accepted Answer · 2021-04-24 12:04:31Z

1

You can do 2 steps:

Group data by terms
Filter data when data in a group greater than 1 item. Otherwise, keep the data in the group which have only one item.

if(values.length > 1) values = values.filter(r => r.id !== "");

const myarray=[{"id":"","AlphaNumber":"ADF12345","terms":"1"},{"id":"ABC12345","AlphaNumber":"LL8888","terms":"1"},{"id":"","AlphaNumber":"KK6666","terms":"2"},{"id":"","AlphaNumber":"QQ1111","terms":"3"},{"id":"ABC12346","AlphaNumber":"RR4444","terms":"3"},{"id":"","AlphaNumber":"SS1111","terms":"5"},{"id":"ABC12347","AlphaNumber":"ASQE223","terms":"5"}];
const result = [];

// Step 1
const groupingData = myarray.reduce((acc, curr) => {
  acc[curr.terms] ??= [];
  acc[curr.terms].push(curr);
  return acc;
}, {});

// Step 2
for(let [key, values] of Object.entries(groupingData)){
  if(values.length > 1) values = values.filter(r => r.id !== "");
  result.push(values);
}
console.log(result.flat());

edited Apr 24, 2021 at 12:04

answered Apr 24, 2021 at 11:59

Nguyễn Văn Phong

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4 Comments

Som Shekhar Mukherjee Over a year ago

Two problems with your current solution: 1) If there are 2 items where term is same but id is empty for both, then resultant would not have any objects with this term.

Som Shekhar Mukherjee Over a year ago

2) If there are 2 items where term is same and id is not empty for both, then resultant would have both objects with this term.

Nguyễn Văn Phong Over a year ago

I don't think so. You can read the OP's requirement again and check my output answer

Som Shekhar Mukherjee Over a year ago

For OP's current input it works but for other inputs it might fail. Consider this input [{ id: "", AlphaNumber: "ADF12345", terms: "1" }, { id: "", AlphaNumber: "LL8888", terms: "1" }]

AbsoluteBeginner · Accepted Answer · 2021-04-24 12:44:35Z

0

My suggestion:

const array = [{
    id: "",
    AlphaNumber: "ADF12345",
    terms: "1"
  }, {
    id: "ABC12345",
    AlphaNumber: "LL8888",
    terms: "1"
  }, {
    id: "",
    AlphaNumber: "KK6666",
    terms: "2"
  }, {
    id: "",
    AlphaNumber: "QQ1111",
    terms: "3"
  }, {
    id: "ABC12346",
    AlphaNumber: "RR4444",
    terms: "3"
  }, {
    id: "",
    AlphaNumber: "SS1111",
    terms: "5"
  }, {
    id: "ABC12347",
    AlphaNumber: "ASQE223",
    terms: "5"
  }],

  obj = {};

for (const o of array) obj[o.terms]?.id || (obj[o.terms] = o);

More about Optional chaining (?.)

answered Apr 24, 2021 at 12:44

AbsoluteBeginner

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