Get non unique records from json array node js

Question

I have one requirement that will get json array object it looks like below(input) json i need to get dupliacte records & unquie records and load it into respective list. condition to check wether array has duplicates or not :: id

let uniqueList = [];
let dupList = [];

Array.prototype.contains = function (item) {
    let filtered_item = this.filter((i) => {
        return i.id === item.id
    });
    return !!filtered_item.length;
}

function contains(list, item) {
    let filtered_item = list.filter((i) => {
        return i.id === item.id
    });
    return !!filtered_item.length;
}

function pushToUniqueList(item) {
    uniqueList.push(item);
}

function pushToDuplicateList(item) {
    dupList.push(item);
}

for (let i = 0; i < objList.length; i++) {
    if (uniqueList.contains(objList[i])) {
        pushToDuplicateList(objList[i]);
    } else {
        pushToUniqueList(objList[i]);
    }
}
Input : [{"obj":{"id":"1234","table":"123"}},{"obj":{"id":"1234","table":"123"}},{"obj":{"id":"12344","table":"123"}}]
output : uniqueList =[{ "obj":{ "id":"12344", "table":"123" }]
dupList =[{"obj":{"id":"1234","table":"123"}},{"obj":{"id":"1234","table":"123"}}]

I have tried with above code but its not working Please help!Thanks in advance!

Can you add to your question what is the input and what is the current output as well as expected output? — Molda
– Molda, Commented Jun 18, 2021 at 17:39
Input [{ "obj":{ "id":"1234", "table":"123" } }, { "obj":{ "id":"1234", "table":"123" } }, { "obj":{ "id":"12344", "table":"123" } }] output : uniqueList =[{ "obj":{ "id":"12344", "table":"123" }] dupList =[{ "obj":{ "id":"1234", "table":"123" } }, { "obj":{ "id":"1234", "table":"123" } }] @Molda — Hari
– Hari, Commented Jun 18, 2021 at 18:01

bhaginath · Accepted Answer · 2021-06-18 19:57:14Z

2

You can try the below, this code runs in linear time

const data = [
      { obj: { id: "1234", table: "123" } },
      { obj: { id: "1234", table: "123" } },
      { obj: { id: "12344", table: "123" } },
    ];
    
    const map = new Map();
    
    for (const entry of data) {
      if (map.has(entry.obj.id)) {
        map.get(entry.obj.id).push(entry);
      } else {
        map.set(entry.obj.id, [entry]);
      }
    }
    
    const uniques = [];
    const duplicates = [];
    
    for (const [id, values] of map.entries()) {
      if (values.length > 1) {
        duplicates.push(...values);
      } else {
        uniques.push(...values);
      }
    }
    
    console.log(`duplicates: ${JSON.stringify(duplicates)}`);
    console.log(`unique: ${JSON.stringify(uniques)}`);

Output

[
  { obj: { id: '1234', table: '123' } },
  { obj: { id: '1234', table: '123' } }
] [ { obj: { id: '12344', table: '123' } } ]

edited Jun 18, 2021 at 19:57

bhaginath

4564 silver badges13 bronze badges

answered Jun 18, 2021 at 18:16

yondu_udanta

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