Update isDuplicates.md

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Angelos Chalaris
2020-10-04 16:16:30 +03:00
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---
title: isDuplicates
tags: array,intermediate
title: hasDuplicates
tags: array,beginner
---
Check if there's duplicate values in a flat array.
- Convert original array into a Set.
- The `Set.prototype.size` returns the number of (unique) elements in a Set object.
- Compare the lengths of the array and the Set.
Checks if there are duplicate values in a flat array.
- Use `Set()` to get the unique values in the array.
- Use `Set.prototype.size` and `Array.prototype.length` to check if the count of the unique values is the same as elements in the original array.
```js
function isDuplicates(array) {
return new Set(array).size !== array.length
}
const hasDuplicates = arr => new Set(arr).size !== arr.length;
```
```js
isDuplicates([0,1,1,2]); // 'True'
isDuplicates([0,1,2,3,]); // 'False'
hasDuplicates([0,1,1,2]); // true
hasDuplicates([0,1,2,3,]); // false
```