es-toolkit/docs/reference/array/maxBy.md

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# maxBy
Finds the element in an array that has the maximum value when applying the `getValue` function to each element.
If the list is empty, returns `undefined`.
## Signature
```typescript
function maxBy<T>(items: T[], getValue: (item: T) => number): T;
```
### Parameters
- `items` (`T[]`): The array of elements to search.
- `getValue` (`(item: T) => number`): A function that selects a numeric value from each element.
### Returns
The element with the maximum value as determined by the `getValue` function.
### Example
```typescript
maxBy([{ a: 1 }, { a: 2 }, { a: 3 }], x => x.a); // Returns: { a: 3 }
maxBy([], x => x.a); // Returns: undefined
```