how to get duplicate values from array in javascript
var array = [1, 2, 2, 3, 3, 4, 5, 6, 2, 3, 7, 8, 5, 22, 1, 2, 511, 12, 50, 22];
console.log([...new Set(
array.filter((value, index, self) => self.indexOf(value) !== index))]
);how to get duplicate values from array in javascript
var array = [1, 2, 2, 3, 3, 4, 5, 6, 2, 3, 7, 8, 5, 22, 1, 2, 511, 12, 50, 22];
console.log([...new Set(
array.filter((value, index, self) => self.indexOf(value) !== index))]
);find duplicates in array
function findDuplicates(arr) {
const duplicates = new Set()
return arr.filter(item => {
if (duplicates.has(item)) {
return true
}
duplicates.add(item)
return false
})
}javascript find duplicate in array
// JavaScript - finds if there is duplicate in an array.
// Returns True or False.
const isThereADuplicate = function(arrayOfNumbers) {
// Create an empty associative array or hash.
// This is preferred,
let counts = {};
// // but this also works. Comment in below and comment out above if you want to try.
// let counts = [];
for(var i = 0; i <= arrayOfNumbers.length; i++) {
// As the arrayOfNumbers is being iterated through,
// the counts hash is being populated.
// Each value in the array becomes a key in the hash.
// The value assignment of 1, is there to complete the hash structure.
// Once the key exists, meaning there is a duplicate, return true.
// If there are no duplicates, the if block completes and returns false.
if(counts[arrayOfNumbers[i]] === undefined) {
counts[arrayOfNumbers[i]] = 1;
} else {
return true;
}
}
return false;
}check for duplicates in array javascript
[1, 2, 3].every((e, i, a) => a.indexOf(e) === i) // true
[1, 2, 1].every((e, i, a) => a.indexOf(e) === i) // falsefind duplicate values in array javascript
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)}`);find duplicate values in array javascript
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)}`);Copyright © 2021 Codeinu
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