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how to find duplicate elements in array in javascript

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Chetan Nada answered on June 19, 2020 Popularity 1/10 Helpfulness 1/10

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how to find duplicate elements in array in javascript

Comment

const arry = [1, 2, 6, 6, 3, 4, 3, 5];

const toFindDuplicates = arry.filter((item, index) => arry.indexOf(item) !== index)
console.log(toFindDuplicates);

// Output: [6, 3]

Popularity 1/10 Helpfulness 1/10 Language javascript

Source: Grepper

Tags: elements find javascript

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Contributed on May 27 2023

Chetan Nada

0 Answers Avg Quality 2/10

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find duplicates in array javascript

Comment

let arr = [1, 2, 3, 4, 5, 5];
const seen = new Set();
const duplicates = arr.filter(n => seen.size === seen.add(n).size);
console.log(duplicates); // [ 5 ]
console.log(duplicates.length); // 1

Popularity 10/10 Helpfulness 5/10 Language javascript

Source: Grepper

Tags: find

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Contributed on Jun 30 2022

slohobo

0 Answers Avg Quality 2/10

count duplicate elements in array javascript

Comment

const counts = {};
const sampleArray = ["1", "5", "9", "14", "5", "22", "48", "25", "22", "20", "9" ,"13"]
sampleArray.forEach(function (x) { counts[x] = (counts[x] || 0) + 1; });
console.log(counts)
 // output: {
  '1': 1,
  '5': 2,
  '9': 2,
  '13': 1,
  '14': 1,
  '20': 1,
  '22': 2,
  '25': 1,
  '48': 1
}

Popularity 10/10 Helpfulness 5/10 Language javascript

Source: stackoverflow.com

Tags: count coun

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Contributed on May 18 2022

Mizanur Rahman

0 Answers Avg Quality 2/10

find duplicates in array javascript

Comment

function findDuplicates(arr) {
    let seen = {};
    let duplicates = [];
    for (let i = 0; i < arr.length; i++) {
        if (seen[arr[i]]) {
            duplicates.push(arr[i]);
        } else {
            seen[arr[i]] = true;
        }
    }
    return duplicates;
}

Popularity 8/10 Helpfulness 5/10 Language javascript

Source: Grepper

Tags: find javascript javascr

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Contributed on Jan 25 2024

kvz

0 Answers Avg Quality 2/10

find duplicate values in array javascript

Comment

const findDuplicates = (arr) => {
  let sorted_arr = arr.slice().sort(); // You can define the comparing function here. 
  // JS by default uses a crappy string compare.
  // (we use slice to clone the array so the
  // original array won't be modified)
  let results = [];
  for (let i = 0; i < sorted_arr.length - 1; i++) {
    if (sorted_arr[i + 1] == sorted_arr[i]) {
      results.push(sorted_arr[i]);
    }
  }
  return results;
}

let duplicatedArray = [9, 4, 111, 2, 3, 4, 9, 5, 7];
console.log(`The duplicates in ${duplicatedArray} are ${findDuplicates(duplicatedArray)}`);

Popularity 10/10 Helpfulness 5/10 Language javascript

Source: stackoverflow.com

Tags: find

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Contributed on Jan 09 2021

Fancy Fish

0 Answers Avg Quality 2/10

check for duplicates in array javascript

Comment

[1, 2, 3].every((e, i, a) => a.indexOf(e) === i) // true

[1, 2, 1].every((e, i, a) => a.indexOf(e) === i) // false

Popularity 10/10 Helpfulness 4/10 Language javascript

Source: stackoverflow.com

Tags: javascript j

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Contributed on Jan 01 2021

Repulsive Rhinoceros

0 Answers Avg Quality 2/10

how to get duplicate values from array in javascript

Comment

var input = [1, 2, 3, 1, 3, 1];

var duplicates = input.reduce(function(acc, el, i, arr) {
  if (arr.indexOf(el) !== i && acc.indexOf(el) < 0) acc.push(el); return acc;
}, []);

document.write(duplicates); // = 1,3 (actual array == [1, 3])

Popularity 10/10 Helpfulness 4/10 Language javascript

Source: stackoverflow.com

Tags: get

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Contributed on Jun 19 2020

Restu Wahyu Saputra

0 Answers Avg Quality 2/10

how to get duplicate values from array in javascript

Comment

const names = ['Mike', 'Matt', 'Nancy', 'Adam', 'Jenny', 'Nancy', 'Carl']

const count = names =>
  names.reduce((a, b) => ({ ...a,
    [b]: (a[b] || 0) + 1
  }), {}) // don't forget to initialize the accumulator

const duplicates = dict =>
  Object.keys(dict).filter((a) => dict[a] > 1)

console.log(count(names)) // { Mike: 1, Matt: 1, Nancy: 2, Adam: 1, Jenny: 1, Carl: 1 }
console.log(duplicates(count(names))) // [ 'Nancy' ]

Popularity 10/10 Helpfulness 4/10 Language javascript

Source: stackoverflow.com

Tags: get

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Contributed on Jun 19 2020

Restu Wahyu Saputra

0 Answers Avg Quality 2/10

Find duplicate or repeat elements in js array

Comment

-1

function findUniq(arr) {
  return arr.find(n => arr.indexOf(n) === arr.lastIndexOf(n));
}

console.log(findUniq([ 0, 1, 0 ]))
console.log(findUniq([ 1, 1, 1, 2, 1, 1 ]))
console.log(findUniq([ 3, 10, 3, 3, 3 ]))
console.log(findUniq([ 7, 7, 7, 20, 7, 7, 7 ]))

Popularity 10/10 Helpfulness 4/10 Language javascript

Source: Grepper

Tags: elements element

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Contributed on Oct 11 2021

Wide-eyed Wolf

0 Answers Avg Quality 2/10

how to get duplicate values from array in javascript

Comment

const arr = ["q", "w", "w", "e", "i", "u", "r"]
arr.reduce((acc, cur) => { 
  if(acc[cur]) {
    acc.duplicates.push(cur)
  } else {
    acc[cur] = true //anything could go here
  }
}, { duplicates: [] })

Popularity 10/10 Helpfulness 4/10 Language javascript

Source: stackoverflow.com

Tags: get

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Contributed on Jun 19 2020

Restu Wahyu Saputra

0 Answers Avg Quality 2/10

find duplicate values in array javascript

Comment

const findDuplicates = (arr) => {
  let sorted_arr = arr.slice().sort(); // You can define the comparing function here. 
  // JS by default uses a crappy string compare.
  // (we use slice to clone the array so the
  // original array won't be modified)
  let results = [];
  for (let i = 0; i < sorted_arr.length - 1; i++) {
    if (sorted_arr[i + 1] == sorted_arr[i]) {
      results.push(sorted_arr[i]);
    }
  }
  return results;
}

let duplicatedArray = [9, 4, 111, 2, 3, 9, 4, 5, 7];
console.log(`The duplicates in ${duplicatedArray} are ${findDuplicates(duplicatedArray)}`);

Popularity 10/10 Helpfulness 3/10 Language javascript

Source: stackoverflow.com

Tags: find

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Contributed on Jan 09 2021

Fancy Fish

0 Answers Avg Quality 2/10

how to find duplicate elements in array in javascript

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how to find duplicate elements in array in javascript

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find duplicates in array javascript

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find duplicates in array javascript

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check for duplicates in array javascript

how to get duplicate values from array in javascript

how to get duplicate values from array in javascript

Find duplicate or repeat elements in js array

how to get duplicate values from array in javascript

find duplicate values in array javascript

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