JavaScript Iterator flatMap()
Example
// Create an iterator
const myIterator = Iterator.from([1, 2, 3, 4, 5, 6]);
// Map the Iterator
const mappedIterator = myIterator.flatMap(x => [x, x * 10]);
Try it Yourself »
Description
The flatMap() method maps all iterator elements and creates a new flat iterator.
flatMap() creates a new iterator from calling a
function for every array element.
flatMap() does not execute the function for empty elements.
flatMap() does not change the original iterator.
Syntax
iterator.flatMap(function(currentValue, index, arr), thisValue)
Parameters
| Parameter | Description |
| function() | Required. A function to be run for each iterator element. |
| currentValue | Required. The value of the current element. |
| index | Optional. The index of the current element. |
| arr | Optional. The iterator of the current element. |
| thisValue | Optional. Default value undefined.A value passed to the function to be used as its this value. |
Return Value
| Type | Description |
| Iterator | An iterator with the elements as a result of a callback function and then flattened. |
Browser Support
iterator.flatMap() is an ES2025 feature.
ES2025 is fully supported in all modern browsers since May 2025:
| Chrome 135 | Edge 135 | Firefox 129 | Safari 18.2 | Opera 120 |
| Apr 2025 | Apr 2025 | Aug 2024 | Des 2024 | May 2025 |
