You can assign variables from nested arrays like this:
const arr = ["cars", "planes", ["trains", ["motorcycles"]]]
let trans1 = arr[0]
let trans2 = arr[1]
let trans3 = arr[2][0]
let trans4 = arr[2][1][0]
console.log(trans1) // outputs "cars"
console.log(trans2) // outputs "planes"
console.log(trans3) // outputs "trains"
console.log(trans4) // outputs "motorcycles"
With ES6, you can assign variables from arrays in a much more succinct way.