Question

我制作了这个代码，将数组转换为

下面的列表

// This is a function to make a list from an array
// This is a recursive function
function arrayToList(array) {
    // I use an object constructor notation here
    var list = new Object();
    // This is to end the recursion, if array.length == 1, the function won't call itself and instead
    // Just give rest = null
    if (array.length == 1) {
        list.value = array[array.length - 1];
        list.rest = null;
        return list;
    } else {
        // This is to continue the recursion.  If the array.length is not == 1, make the rest key to call arrayToList function
        list.value = array[0];
        // To avoid repetition, splice the array to make it smaller
        array.splice(0,1);
        list.rest = arrayToList(array);
        return list;
    }
}

arrayToList([1, 2]);

但是，现在我正在尝试颠倒这个过程，即编写一个从列表中返回数组的函数。

所以我希望功能如下所示

listToArray(function(arrayToList([1,2])
=> [1,2]

我该怎么做，请帮帮忙？

Answer 1

以下是代码：

function listToArray(list) {
    var array = [];
    var item = list;
    while (item) {
        array.push(item.value);
        item = item.rest;
    }
    return array;
}

Answer 2

很抱歉发布完整代码，但我这样做是为了便于理解：

function arrayToList(arr) {
  var li = {};
  li.value=arr[0], arr.shift();
  if(arr.length) li.rest=arrayToList(arr);
  else li.rest=null; 
  return li;
}
function listToArray(li) {
  var arr = [];
  for(var i=li; i; i=i.rest) arr.push(i.value);
  return arr;
}
function prepend(a, b) {
  var li = {};
  li.value=a, li.rest=b;
  return li;
}
function nth(li, n) {
  var elem, cnt=0;
  for(var i=li; i; i=i.rest, cnt++) {
    if(cnt==n) {
      elem=i.value;
      break;
    }
  }
  return elem;
}

console.log(arrayToList([10, 20]));
// → {value: 10, rest: {value: 20, rest: null}}
console.log(listToArray(arrayToList([10, 20, 30])));
// → [10, 20, 30]
console.log(prepend(10, prepend(20, null)));
// → {value: 10, rest: {value: 20, rest: null}}
console.log(nth(arrayToList([10, 20, 30]), 1));
// → 20

listToArray的功能（函数（arrayToList（array）

2 个答案: