find duplicate string in array javascript
let strArray = [ "q", "w", "w", "w", "e", "i", "u", "r"];
let findDuplicates = arr => arr.filter((item, index) => arr.indexOf(item) != index)
console.log(findDuplicates(strArray)) // All duplicates
console.log([...new Set(findDuplicates(strArray))]) // Unique duplicatescheck 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) // falsehow to get duplicate values from array in javascript
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' ]Copyright © 2021 Codeinu
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