List data structures in JavaScript

Question

In an exercise in the book Eloquent JavaScript I need to create a list data structure (as below) based on the array [1, 2, 3].

The tutorial JavaScript

Answer 1

function arrayToList (arr) {
    var list = null;
    for (var i = arr.length - 1; i >= 0; i--) {
        list = {
            value: arr[i],
            rest: list
        };
    }
    return list;
}

function prepend (elem, list) {
    return {
        value: elem,
        rest: list
    };
}

function listToArray (list) {
    var arr = [];
    for (var node = list; node; node = node.rest) {
        arr.push(node.value);
    }
    return arr;
}

function nth(list, num) {
  if (!list) {
    return undefined;
    } else if (num === 0) {
        return list.value;
    } else {
        return nth(list.rest, num - 1);
    }
}