How to remove duplicate object in javascript?

Question

I have object like this :

cons data = []
const result =
[
    {
        "result_id": "AAA877",
        "emp_id": 1,
        "hashtag": [
            {
                "result_id": "AAA877",
                "hashtag_id": 1,
                "apptype_id": 3,
                "tag": {
                    "id": 1,
                    "name": "NodeJs",
                    "hashtag_group_id": 1
                }
            }
        ]
    },
    {
        "result_id": "AAAAA1",
        "emp_id": 1,
        "hashtag": [
            {
                "result_id": "AAAAA1",
                "hashtag_id": 1,
                "apptype_id": 4,
                "tag": {
                    "id": 1,
                    "name": "NodeJs",
                    "hashtag_group_id": 1
                }
            }
        ]
    },
    {
        "result_id": "AAB238",
        "emp_id": 1,
        "hashtag": [
            {
                "result_id": "AAB238",
                "hashtag_id": 2,
                "apptype_id": 4,
                "tag": null
            }
        ]
    },
    {
        "result_id": "AAB415",
        "emp_id": 1,
        "hashtag": [
            {
                "result_id": "AAB415",
                "hashtag_id": 1,
                "apptype_id": 3,
                "tag": {
                    "id": 1,
                    "name": "NodeJs",
                    "hashtag_group_id": 1
                }
            }
        ]
    },
    {
        "result_id": "AAD668",
        "emp_id": 2,
        "hashtag": [
            {
                "result_id": "AAD668",
                "hashtag_id": 1,
                "apptype_id": 3,
                "tag": {
                    "id": 1,
                    "name": "NodeJs",
                    "hashtag_group_id": 1
                }
            }
        ]
    },
    {
        "result_id": "AAG239",
        "emp_id": 1,
        "hashtag": [
            {
                "result_id": "AAG239",
                "hashtag_id": 4,
                "apptype_id": 3,
                "tag": null
            }
        ]
    },
    {
        "result_id": "AAH740",
        "emp_id": 1,
        "hashtag": [
            {
                "result_id": "AAH740",
                "hashtag_id": 2,
                "apptype_id": 3,
                "tag": null
            }
        ]
    },
    {
        "result_id": "AAK119",
        "emp_id": 2,
        "hashtag": [
            {
                "result_id": "AAK119",
                "hashtag_id": 1,
                "apptype_id": 4,
                "tag": {
                    "id": 1,
                    "name": "NodeJs",
                    "hashtag_group_id": 1
                }
            }
        ]
    },
    {
        "result_id": "AAK298",
        "emp_id": 1,
        "hashtag": [
            {
                "result_id": "AAK298",
                "hashtag_id": 2,
                "apptype_id": 3,
                "tag": null
            }
        ]
    }
]

I want to filter and push emp_id and apptype_id without a duplicate

This is what i expected :

[
  { emp_id: 1, app_type_id: 3 },
  { emp_id: 1, app_type_id: 4 },
  { emp_id: 2, app_type_id: 3 },
  { emp_id: 2, app_type_id: 4 }
]

I was trying like this :

result.forEach(r => {
        if (r.hashtag[0].tag !== null) {
          const t = {
            emp_id: r.emp_id,
            app_type_id: r.hashtag[0].apptype_id
          }
          if (data.indexOf(t) === -1) {
            data.push(t)
          }
        }
      })

But what i got was like this :

[
  { emp_id: 1, app_type_id: 3 },
  { emp_id: 1, app_type_id: 4 },
  { emp_id: 1, app_type_id: 3 },
  { emp_id: 2, app_type_id: 3 },
  { emp_id: 2, app_type_id: 4 }
]

How to filter without a duplicate like what i expected ?

Please ask me if you need more information if it's still not enough

Assuming the hashtag array always has one item in it, I would approach this with Array.reduce method. That is, create a new array by reduce method that organizes the data by emp_id, then build a final result array by map that massages the output. — Bumhan Yu
– Bumhan Yu, Commented May 13, 2022 at 13:50

Andy · Accepted Answer · 2022-05-13 14:08:36Z

2

An alternative approach. Loop over the data, destructure the properties you want into a new object, stringify that, and push that string into a temporary array. Then, on every next iteration, check to see if that string has already been created. If it hasn't push that string into the array.

Finally map over the strings and parse each one to produce an array of objects that matches your expected output.

const data=[{result_id:"AAA877",emp_id:1,hashtag:[{result_id:"AAA877",hashtag_id:1,apptype_id:3,tag:{id:1,name:"NodeJs",hashtag_group_id:1}}]},{result_id:"AAAAA1",emp_id:1,hashtag:[{result_id:"AAAAA1",hashtag_id:1,apptype_id:4,tag:{id:1,name:"NodeJs",hashtag_group_id:1}}]},{result_id:"AAB238",emp_id:1,hashtag:[{result_id:"AAB238",hashtag_id:2,apptype_id:4,tag:null}]},{result_id:"AAB415",emp_id:1,hashtag:[{result_id:"AAB415",hashtag_id:1,apptype_id:3,tag:{id:1,name:"NodeJs",hashtag_group_id:1}}]},{result_id:"AAD668",emp_id:2,hashtag:[{result_id:"AAD668",hashtag_id:1,apptype_id:3,tag:{id:1,name:"NodeJs",hashtag_group_id:1}}]},{result_id:"AAG239",emp_id:1,hashtag:[{result_id:"AAG239",hashtag_id:4,apptype_id:3,tag:null}]},{result_id:"AAH740",emp_id:1,hashtag:[{result_id:"AAH740",hashtag_id:2,apptype_id:3,tag:null}]},{result_id:"AAK119",emp_id:2,hashtag:[{result_id:"AAK119",hashtag_id:1,apptype_id:4,tag:{id:1,name:"NodeJs",hashtag_group_id:1}}]},{result_id:"AAK298",emp_id:1,hashtag:[{result_id:"AAK298",hashtag_id:2,apptype_id:3,tag:null}]}];

const temp = [];

for (const obj of data) {
  const { emp_id, hashtag: [{ apptype_id }] } = obj;
  const newObj = { emp_id, app_type_id: apptype_id };
  const str = JSON.stringify(newObj);
  if (!temp.includes(str)) temp.push(str);
}

const out = temp.map(str => JSON.parse(str));
console.log(out);

edited May 13, 2022 at 14:08

answered May 13, 2022 at 14:00

Andy

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3 Comments

Cesare Polonara Over a year ago

I think that even without stringifying the object it would work since it would compare the memory address. This solution assumes that there's only one element inside the hastag array, if there's more than one ( since it's an array it's a legit assumption ) it would need some extra tweaks.

Andy Over a year ago

@CesarePolonara OP already told me that hashtag would only have one object (see comments).

Cesare Polonara Over a year ago

Ok sorry, I missed it !

scottmcgowan · Accepted Answer · 2022-05-13 14:03:49Z

0

I would run a filter on the objects that you have before extracting the info! This should do the trick:

var removed_duplicates = result.filter((result, index, self) =>
    index === self.findIndex((other_entry) => 
        (other_entry.emp_id === result.emp_id && 
         other_entry.hashtag[0].apptype_id === result.hashtag[0].apptype_id)))

What this does is it filters your original entries by looking for other entries in the list with the same values that you're trying to filter on. If there are none, then the returned index will be the same, otherwise it will succeed for the first encounter with one of the duplicate entries but fail for all of the following ones, causing them to be removed.

answered May 13, 2022 at 14:03

scottmcgowan

72 bronze badges

1 Comment

user18605090 Over a year ago

thanks for answering my question! :D

Nina Scholz · Accepted Answer · 2022-05-13 14:05:23Z

You could get an array of objects and filter with a Set.

const
    data = [{ result_id: "AAA877", emp_id: 1, hashtag: [{ result_id: "AAA877", hashtag_id: 1, apptype_id: 3, tag: { id: 1, name: "NodeJs", hashtag_group_id: 1 } }] }, { result_id: "AAAAA1", emp_id: 1, hashtag: [{ result_id: "AAAAA1", hashtag_id: 1, apptype_id: 4, tag: { id: 1, name: "NodeJs", hashtag_group_id: 1 } }] }, { result_id: "AAB238", emp_id: 1, hashtag: [{ result_id: "AAB238", hashtag_id: 2, apptype_id: 4, tag: null }] }, { result_id: "AAB415", emp_id: 1, hashtag: [{ result_id: "AAB415", hashtag_id: 1, apptype_id: 3, tag: { id: 1, name: "NodeJs", hashtag_group_id: 1 } }] }, { result_id: "AAD668", emp_id: 2, hashtag: [{ result_id: "AAD668", hashtag_id: 1, apptype_id: 3, tag: { id: 1, name: "NodeJs", hashtag_group_id: 1 } }] }, { result_id: "AAG239", emp_id: 1, hashtag: [{ result_id: "AAG239", hashtag_id: 4, apptype_id: 3, tag: null }] }, { result_id: "AAH740", emp_id: 1, hashtag: [{ result_id: "AAH740", hashtag_id: 2, apptype_id: 3, tag: null }] }, { result_id: "AAK119", emp_id: 2, hashtag: [{ result_id: "AAK119", hashtag_id: 1, apptype_id: 4, tag: { id: 1, name: "NodeJs", hashtag_group_id: 1 } }] }, { result_id: "AAK298", emp_id: 1, hashtag: [{ result_id: "AAK298", hashtag_id: 2, apptype_id: 3, tag: null }] }],
    result = data
        .flatMap(({ emp_id, hashtag }) => hashtag.map(({ apptype_id }) => ({ emp_id, apptype_id })))
        .filter((s => ({ emp_id, apptype_id }) => {
            const key = [emp_id, apptype_id].join('|');
            if (!s.has(key)) return s.add(key);
        })(new Set));

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

random322 · Accepted Answer · 2022-05-13 13:51:06Z

-1

There is no structure comparison in JS, objects are compared by their "addresses in memory", you have to compare primitive values ([].indexOf(t) compares items of array with t).

console.log({text: 'hey'} !== {text: 'hey'})

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Equality_comparisons_and_sameness

answered May 13, 2022 at 13:51

random322

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