:title
dv_map

:sig
DValue dv_map(DValue tree, function<DValue (DValue, String)> f)

:see
StringList
0_DValue
filter

:content
Transforms each child. List-like input stays list-like; map input keeps keys.

These helpers keep common data-shaping code close to render code, routers, and configuration trees. They are useful for route lists, navigation items, cards, and records that need simple transformations before rendering.

```cpp
DValue titles = dv_map(items, [](DValue item, String key) { DValue out; out = item["title"].to_string(); return(out); });
```

Prefer these helpers over open-coded loops when the transformation itself is the important part of the code. Use an explicit loop when mutation, error handling, or side effects are the main concern.

## Related Concepts

- JavaScript / React: `Array.map`, `Array.filter`, `Array.find`, object `pick`/`omit`, and grouping route or navigation records before rendering.
- PHP: `array_map`, `array_filter`, `array_unique`, and associative array projection.