JSFiddle - React, Tailwind, and code Playground

by Alex Myronov

JavaScript

const flatten = (array) => {
	if (!array) return []

	return array.reduce((result, item) => {
		if (Array.isArray(item)) {
			return [...result, ...flatten(item)]
		}
		return [...result, item]
	}, [])
}

console.log(flatten([12, [123], [[12, 1], 2], 89]))