`Array.prototype.flatMap()`

Maps each element with a callback then flattens the result by one level.

Since ES2019 Spec ↗

Syntax

arr.flatMap(callback, thisArg)

Name	Type	Required	Description
`callback`	`Function`	Yes	Function called with (element, index, array). May return a value or an array.
`thisArg`	`any`	No	Value to use as `this` when executing the callback.

Array — A new array with each callback result flattened by one level.

console.log([1, 2, 3].flatMap(n => [n, n * 2]));

Output

[ 1, 2, 2, 4, 3, 6 ]

console.log(['a b', 'c'].flatMap(s => s.split(' ')));

Output

[ 'a', 'b', 'c' ]

Equivalent to `.map(fn).flat(1)` but more efficient. Only flattens one level. Returning an empty array effectively removes an element.