const yourArray = [1, 1, 2, 3, 4, 5, 5]
let duplicates = []
const tempArray = [...yourArray].sort()
for (let i = 0; i < tempArray.length; i++) {
if (tempArray[i + 1] === tempArray[i]) {
duplicates.push(tempArray[i])
}
}
console.log(duplicates) //[ 1, 5 ]const yourArray = [1, 1, 2, 3, 4, 5, 5]
const yourArrayWithoutDuplicates = [...new Set(yourArray)]
let duplicates = [...yourArray]
yourArrayWithoutDuplicates.forEach((item) => {
const i = duplicates.indexOf(item)
duplicates = duplicates
.slice(0, i)
.concat(duplicates.slice(i + 1, duplicates.length))
})
console.log(duplicates) //[ 1, 5 ]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: [] })var names = ['Mike', 'Matt', 'Nancy', 'Adam', 'Jenny', 'Nancy', 'Carl']
var uniq = names
.map((name) => {
return {
count: 1,
name: name
}
})
.reduce((a, b) => {
a[b.name] = (a[b.name] || 0) + b.count
return a
}, {})
var duplicates = Object.keys(uniq).filter((a) => uniq[a] > 1)
console.log(duplicates) // [ 'Nancy' ]