ArrayprototypeflatMap

Array.prototype.flatMap is a method in JavaScript that maps each element using a mapping function and then flattens the result into a new array. It is equivalent to a map followed by a flat with a depth of 1. The mapping function is called for each element in the array and can return an array, a single value, or nothing. If the mapping function returns an array, its elements are included in the resulting array. If it returns a single value, that value is included. If it returns nothing, nothing is added for that element.

The flatMap method can be useful for scenarios where you need to transform elements and potentially expand them into multiple elements, or filter them out entirely, all in a single operation. For example, if you have an array of strings and want to split each string into an array of characters, flatMap can achieve this efficiently. It iterates over the original array, applies the provided callback function to each element, and then flattens the array returned by the callback into a new, single-level array.

The callback function provided to flatMap receives three arguments: the current element being processed, the index of the current element, and the array flatMap was called upon. The method does not mutate the original array; it always returns a new array. This makes it a non-destructive operation, preserving the integrity of the source data.