使用递归创建 JSON 字符串（复制 stringify）

Question

我正在尝试使用递归复制 JSON.stringify()。我有点困惑为什么我在返回的 JSON 字符串中没有定义。这是我到目前为止所做的：

var testobj = {num:123,str:"This is a string",bool:true,o:{x:1,y:2},iamnull:null}
var count = 0
var stringifyJSON = function(obj) {

  // your code goes here
  if(obj === undefined){ 
  	return console.log("obj was undefined");
  }
  count = count + 1
  if(count > 20){  //I put this here mostly to stop infinite loops assuming this function wouldn't occur over 20 times.
  	return console.log("failed")
  }  
  var endarray = [];
if(obj !== undefined && typeof(obj)==='object'){  //If the object isn't undefined and the object is an object...

  for(var prop in obj){
   	console.log('"' + prop + '"');
  	endarray.push(stringifyJSON(prop) +'"' + ':' +'"'+ stringifyJSON(obj[prop])) //push the items into the array, using recursion. 
  }
  if(typeof(obj) !== undefined){
  	return '{' + endarray.join() + '}'
  }
}

  
  
};

//end result is "{undefined":"undefined,undefined":"undefined,undefined":"undefined,undefined":"{undefined":"undefined,undefined":"undefined},undefined":"{}}"

//JSON values cannot be a function, a date, or undefined

有人能指出我哪里出错了吗？通过递归，我在确定问题的根源时遇到了问题。

Answer 1

要找到正确的解决方案，需要做几件事。

首先，您没有递归的基本情况，因此在每个递归跟踪的基本级别，不返回任何内容（即隐式返回 undefined）。因此，首先您必须添加一个基本情况，将整数、字符串、布尔值和其他原始类型转换为字符串。

其次，您还必须在递归调用之前检查obj !== null，因为typeof(null) 的计算结果为“对象”，这很奇怪。

var testobj = {num:123,str:"This is a string",bool:true,o:{x:1,y:2},iamnull:null}
var count = 0
var stringifyJSON = function(obj) {

  // your code goes here
  if(obj === undefined){ 
    return console.log("obj was undefined");
  }
  count = count + 1
  if(count > 20){  //I put this here mostly to stop infinite loops assuming this function wouldn't occur over 20 times.
    return console.log("failed")
  }  
  var endarray = [];
if(obj !== undefined && obj !== null && typeof(obj)==='object'){  //If the object isn't undefined and the object is an object...

  for(var prop in obj){
    console.log('"' + prop + '"');
    endarray.push(stringifyJSON(prop) +'"' + ':' +'"'+ stringifyJSON(obj[prop])) //push the items into the array, using recursion. 
  }
  if(typeof(obj) !== undefined){
    return '{' + endarray.join() + '}'
  }
}
if (obj !== undefined) {return String(obj)}


};