Search / Check Methods

includes()

Checks if value exists.

arr.includes(20);

Time: O(n) Mutates? No

indexOf()

Returns first index of value.

arr.indexOf(30);

Time: O(n)

find()

Returns first matching element.

.find(u => u.id === 1);
```e:** O(n)

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<a id="findindex"></a>
## findIndex()

Returns index of first match.

```javascript
users.findIndex(u => u.id === 1);

Time: O(n)

some()

Returns true if any element matches.

arr.some(n => n > 10);

Time: O(n)

every()

Returns true if all elements match.

arr.every(n => n > 0);

Time: O(n)