The flatMap() method of Array instances returns a new array formed by applying a given callback function to each element of the array, and then flattening the result by one level. It is identical to a map() followed by a flat() of depth 1 (arr.map(...args).flat()), but slightly more efficient ...

flatMap() creates a new array from calling a function for every array element.

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September 11, 2019 - The flatMap method works very similarly to flat, but it iterates over every element and flats the result of the passed callback function into a new array.

July 23, 2025 - JavaScript · const numbers = [1, 2, 3, 4]; const doubled = numbers.map(num => num * 2); console.log(doubled); Output · [ 2, 4, 6, 8 ] The flatMap() method first maps each element using the mapping function then flattens the result into a new array.

November 8, 2019 - Array flat removes empty slots in JavaScript arrays · var arrayEmpty = [1, 2, , 4, 5]; arrayEmpty.flat(); // [1, 2, 4, 5] Array flatMap() maps elements array using a mapping function and then flatten the array upto depth of 1.

flatMap can be used as a way to add and remove items (modify the number of items) during a map. In other words, it allows you to map many items to many items (by handling each input item separately), rather than always one-to-one. In this sense, it works like the opposite of filter.

Array.prototype.flatMap() Array.prototype.map() Array.prototype.reduce() Was this page helpful to you? Yes · No Learn how to contribute · This page was last modified on Jul 10, 2025 by MDN contributors.

July 29, 2025 - Explore the differences between map and flatMap in JavaScript, learn their unique use cases, and improve your array manipulation skills with this comprehensive developer's guide.

July 10, 2025 - The flatMap() method of Iterator instances returns a new iterator helper object that takes each element in the original iterator, runs it through a mapping function, and yields elements returned by the mapping function (which are contained in another iterator or iterable).

September 18, 2021 - In this post, we will first see what Array.flatmap() is and then look at how I used it in a real problem.

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June 24, 2024 - The flatMap() method first maps each element using a mapping function, then flattens the result into a new array. It’s a combination of map() followed by flat() of depth 1. const phrases = ["hello world", "javascript is fun"]; // Using map ...

October 10, 2023 - These are flat() and flatmap() which help in flattening arrays. As the name suggests, the flat() method returns a new array with elements of the subarray flattened into it, that is the sub-elements are concatenated into a single array.

ES2019 added the Array flatMap() method to JavaScript.

April 1, 2023 - The flatMap() function in JavaScript is defined as map the elements and making the resultant mapping elements into a new array. This means it makes an into a single dimension array.

Become a certified JavaScript programmer. Try Programiz PRO! ... The flatMap() method first maps each element of an array using a mapping function, then flattens it into a new array.

Use flatMap to map over an array and flatten the result array in one go!

July 26, 2022 - The flatMap() loops through the elements of an array and concatenates the elements into one level.