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 »
const myIterator = Iterator.from([1, 2, 3, 4, 5, 6]);
// Map the Iterator
const mappedIterator = myIterator.flatMap(x => [x, x * 10]);
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.
A function to be run for each iterator element.
currentValue
Required.
The value of the current element.
The value of the current element.
index
Optional.
The index of the current element.
The index of the current element.
arr
Optional.
The iterator of the current element.
The iterator of the current element.
thisValue
Optional.
Default value
A value passed to the function to be used as its
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 a JavaScript 2025 feature.
ES 2025 is fully supported in all modern browsers since May 2025:
| Chrome 136 |
Edge 136 |
Firefox 129 |
Safari 18.2 |
Opera 120 |
| Apr 2025 | Apr 2025 | Aug 2024 | Des 2024 | May 2025 |