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Array.flatMap() is a method introduced in ECMAScript 2019 (ES10) that combines the functionalities of map() and flat() methods. It first maps each element of an array using a mapping function, then flattens the result into a new array. This method is particularly useful when you want to apply a transformation to each element of an array and flatten the resulting arrays into a single array.
Syntax:
array.flatMap(callbackFn[, thisArg])
Parameters:
callbackFn: A function that accepts up to three arguments: the current element being processed, the index of the current element, and the array being mapped.thisArg (optional): An object to which this a keyword can refer to inside the callbackFn.
Example: Here, the flatMap() method is called on the arr array with a callback function that doubles each element of the array and creates a new array containing both the original element and its doubled value.
Javascript
const arr = [1, 2, 3];
const result = arr.flatMap(x => [x, x * 2]);
console.log(result);
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Output
[ 1, 2, 2, 4, 3, 6 ]
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