Extracting data and flattening it from a multi dimensional array

solution.js

//data source = https://gist.github.com/hasinhayder/7352ac2d76660862061ffdd0d963711e

const videos = course.data.chapters
      .map((chapter) => chapter.episodes.map((episode) => episode.vid))
      .flat()

//Another solution (By Shadman Shadab)
const videos = course.data.chapters
      .flatMap((chapter) => chapter.episodes.map((episode) => episode.vid))

// result = ["VAZz_eYJJ1M", "S_pJoNeMqj8", "vmgHZUD0v4c", "mmiPxxulXUk", "nrZAZ0DmrlM"]

const result = course.data.chapters.reduce((acc, curr) => [...acc, ...curr.episodes.map(item => item.vid)], []);