LinkedList

linked_list.js

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

  return list;
}

function listToArray(list) {
  var arr = [];
  while(list != null) {
    arr.push(list.value); 
    list = list.rest;
  }

  return arr;
}

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

function nth(list, n) {
  for(var i=1; i<=n-1;i++) {
    list = list.rest;
    if(list == nul) {
      return undefined;
    }
  }
  return list.value;
}

function insert(list, n, ele) {
  var before = nth(list, n);
  var tmp = before.rest;
  before.rest = {
    value: ele,
    rest: tmp
  }
}

var list = {
  value: 1,
  rest: {
    value: 2,
    rest: {
      value: 3,
      rest: null
    }
  }
};

var arr = [1,2,3];

console.log(arrayToList(arr));
//   => list
console.log(listToArray(list));
//   => arr