Question

我试图使用递归来复制JSON.stringify（）。我对我在返回的JSON字符串中未定义的原因感到有些困惑。这是我到目前为止所做的：

＆＃13;

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

＆＃13;

有人可以指出我哪里出错吗？通过递归，我在确定问题根源时遇到了问题。

Answer 1

要获得正确的解决方案，还需要做几件事。

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）。首先，您必须添加一个基本情况，其中整数，字符串，布尔值和其他基本类型将转换为字符串。

其次，你必须在递归调用之前检查obj !== null，因为typeof(null)评估为“对象”，奇怪的是。

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)}


};

使用递归创建JSON字符串（复制stringify）

1 个答案: