21 lines
539 B
Markdown
21 lines
539 B
Markdown
---
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title: hasDuplicates
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tags: array,beginner
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firstSeen: 2020-10-22T20:23:09+03:00
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lastUpdated: 2020-10-22T20:23:09+03:00
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---
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Checks if there are duplicate values in a flat array.
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- Use `Set` to get the unique values in the array.
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- 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.
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```js
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const hasDuplicates = arr => new Set(arr).size !== arr.length;
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```
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```js
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hasDuplicates([0, 1, 1, 2]); // true
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hasDuplicates([0, 1, 2, 3]); // false
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```
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