# flatMap()
The flatMap method iterates through the collection and passes each value to the given callback. The callback is free to modify the item and return it, thus forming a new collection of modified items. Then, the array is flattened by a level:
const collection = collect([
{
name: 'Darwin Núñez',
number: 27,
},
{
name: 'Mohamed Salah',
number: 11,
},
]);
const flatMapped = collection.flatMap(value => value.name.toUpperCase());
flatMapped.all();
// ['DARWIN NÚÑEZ', 'MOHAMED SALAH']