Javascript - deepEqual 比较

Question

问题(来自 Eloquent Javascript 第 2 版，第 4 章，练习 4):

Write a function, deepEqual, that takes two values and returns true only if they are the same value or are objects with the same properties whose values are also equal when compared with a recursive call to deepEqual.

测试用例:

var obj = {here: {is: "an"}, object: 2};
console.log(deepEqual(obj, obj));
// → true
console.log(deepEqual(obj, {here: 1, object: 2}));
// → false
console.log(deepEqual(obj, {here: {is: "an"}, object: 2}));
// → true

我的代码:

var deepEqual = function (x, y) {
  if ((typeof x == "object" && x != null) && (typeof y == "object" && y != null)) {
    if (Object.keys(x).length != Object.keys(y).length)
      return false;
    for (var prop in x) {
      if (y.hasOwnProperty(prop))
        return deepEqual(x[prop], y[prop]);
    /*This is most likely where my error is. The question states that all the values
    should be checked via recursion; however, with the current setup, only the first
    set of properties will be checked. It passes the test cases, but I would like
    to solve the problem correctly!*/
      }
    }
  else if (x !== y)
    return false;
  else
    return true;
}

我想我已经掌握了总体思路；但是，就像我在评论中所说的那样，程序不会检查对象中的第二个属性。我觉得我有一个结构/逻辑问题并且只是以错误的方式使用递归，因为我最初打算循环遍历属性，使用递归比较第一个属性的值，然后继续循环到下一个属性并再次比较。虽然，我不确定这是否可能？

我已经进行了大量思考并尝试了几种不同的方法，但这是迄今为止我得出的最正确的答案。有什么提示可以指引我正确的方向吗？

Answer 1

如您所料，您正在返回所见第一个属性的匹配项。如果该属性不匹配，您应该返回 false，但继续查找其他情况。

此外，如果在 y 上找不到 prop 属性，则返回 false(即计数匹配，但实际属性不匹配) .

如果所有属性都匹配，返回true:

var deepEqual = function (x, y) {
  if (x === y) {
    return true;
  }
  else if ((typeof x == "object" && x != null) && (typeof y == "object" && y != null)) {
    if (Object.keys(x).length != Object.keys(y).length)
      return false;

    for (var prop in x) {
      if (y.hasOwnProperty(prop))
      {  
        if (! deepEqual(x[prop], y[prop]))
          return false;
      }
      else
        return false;
    }
    
    return true;
  }
  else 
    return false;
}

var deepEqual = function (x, y) {
  if (x === y) {
    return true;
  }
  else if ((typeof x == "object" && x != null) && (typeof y == "object" && y != null)) {
    if (Object.keys(x).length != Object.keys(y).length)
      return false;

    for (var prop in x) {
      if (y.hasOwnProperty(prop))
      {  
        if (! deepEqual(x[prop], y[prop]))
          return false;
      }
      else
        return false;
    }

    return true;
  }
  else 
    return false;
}

var obj = {here: {is: "an", other: "3"}, object: 2};
console.log(deepEqual(obj, obj));
// → true
console.log(deepEqual(obj, {here: 1, object: 2}));
// → false
console.log(deepEqual(obj, {here: {is: "an"}, object: 2}));
// → false
console.log(deepEqual(obj, {here: {is: "an", other: "2"}, object: 2}));
// → false
console.log(deepEqual(obj, {here: {is: "an", other: "3"}, object: 2}));
// → true