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check duplicate value exist in array javascript

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Mehedi Islam Ripon answered on May 27, 2020 Popularity 10/10 Helpfulness 4/10

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check duplicate value exist in array javascript

Comment

function hasDuplicates(array) {
  // create a set to store unique values
  const uniqueValues = new Set();

  // loop through the array
  for (let i = 0; i < array.length; i++) {
    // if the value is not in the set, add it
    if (!uniqueValues.has(array[i])) {
      uniqueValues.add(array[i]);
    } else {
      // if the value is already in the set, return true
      return true;
    }
  }

  // if the loop completes and there are no duplicates, return false
  return false;
}

const numbers = [1, 2, 3, 4, 5];
const hasDuplicates = hasDuplicates(numbers); // returns false

const letters = ['a', 'b', 'c', 'b'];
const hasDuplicates = hasDuplicates(letters); // returns true

Popularity 10/10 Helpfulness 4/10 Language javascript

Source: Grepper

Tags: elements javascript repeat

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Contributed on Dec 05 2022

Mehedi Islam Ripon

0 Answers Avg Quality 2/10

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check if array has same values javascript

Comment

const allEqual = arr => arr.every(v => v === arr[0]);
allEqual([1,1,1,1]);  // true

Popularity 10/10 Helpfulness 6/10 Language javascript

Source: stackoverflow.com

Tags: javascript j

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Contributed on May 27 2020

TC5550

0 Answers Avg Quality 2/10

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 6/10 Language javascript

Source: Grepper

Tags: find

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Contributed on Jun 30 2022

slohobo

0 Answers Avg Quality 2/10

javascript check if array has duplicates

Comment

function hasDuplicates(array) {
    return (new Set(array)).size !== array.length;
}

Popularity 10/10 Helpfulness 5/10 Language javascript

Source: Grepper

Tags: javascript j

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Contributed on Jul 28 2020

Attractive Addax

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 7/10 Helpfulness 5/10 Language javascript

Source: Grepper

Tags: find javascript

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Contributed on Jan 25 2024

kvz

0 Answers Avg Quality 2/10

js find duplicates in array and count of numbers

Comment

const arr = ["a", "b", "c", "d", "e", "a", "b", "c", "f", "g", "h", "h", "h", "e", "a"]
const counts = {};
arr.forEach((x) => {
  counts[x] = (counts[x] || 0) + 1;
});
console.log(counts)

Popularity 10/10 Helpfulness 5/10 Language javascript

Source: thewebdev.info

Tags: count coun

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Contributed on Sep 03 2022

MAKSTYLE119

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

javascript how to check the indexes of duplicates elements in an array

Comment

// A method to find a duplicate value in an array and the index of the duplicates
// array can be any data type
const arry = ["1", "2", "3", "1"];
let set = new Set();
for (let i = 0; i < arry.length; i++) {
  let pastSize = set.size;
  set.add(arry[i]);
  let newSize = set.size;
  if (pastSize == newSize) {
    console.log("The array has duplicates at index: ", i);
  }
}

Popularity 8/10 Helpfulness 4/10 Language javascript

Source: Grepper

Tags: elements element

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Contributed on Oct 24 2022

Al-khatab Yaseen

0 Answers Avg Quality 2/10

javascript check for duplicates in array

Comment

function checkIfDuplicateExists(w){
    return new Set(w).size !== w.length 
}

console.log(
    checkIfDuplicateExists(["a", "b", "c", "a"])
// true
);

console.log(
    checkIfDuplicateExists(["a", "b", "c"]))
//false

Popularity 10/10 Helpfulness 4/10 Language javascript

Source: Grepper

Tags: javascript j

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Contributed on Sep 16 2021

Sbeajy

0 Answers Avg Quality 2/10

check duplicate value exist in array javascript

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