JS实现JSON.stringify的实例代码讲解

/** 
 * JSON stringify的实现 
 * @author norkts<norkts@gmail.com> 
 * @version 1.0 2015-11-24 15:11 实现了基本功能 
 * @version 1.1 2015-11-24 15:19 norkts 增加了JSON.stringify的兼用代码实现 
 * @version 1.2 2015-11-24 15:49 norkts 修改数组indexOf在IE下不兼容的写法,修改了undefined值的特殊处理 
 */ 
(function(NS){ 
 
 //简单类型 
 var simpleTypes = ["number", "boolean", "undefined", "string", "function"]; 
  
 //JSON.stringify的主函数 
 function stringify(object){ 
  var type = typeof object; 
   
  //如果是简单类型，则直接返回简单类型的结果 
  if(indexOf(simpleTypes, type) > -1){ 
   return parseSimpleObject(object); 
  } 
 
  //数组对象的 
  if(object instanceof Array){ 
   var len = object.length; 
   var resArr = []; 
   for(var i = 0; i < len; i++){ 
    var itemType = typeof object[i]; 
    if(indexOf(simpleTypes, itemType) > -1){ 
 
     //undefined特殊处理，数组中变成null 
     if(itemType != "undefined"){ 
      resArr.push(parseSimpleObject(object[i])); 
     }else{ 
      resArr.push("null"); 
     } 
      
    }else{ 
     //递归处理JS数组中的复杂元素 
     resArr.push(stringify(object[i])); 
    } 
   } 
    
   return "[" + resArr.join(",") + "]"; 
  } 
   
  //普通object对象 
  if(object instanceof Object){ 
   if(object == null){ 
    return "null"; 
   } 
    
   var resArr = []; 
    
   for(var name in object){ 
    var itemType = typeof object[name]; 
    if(indexOf(simpleTypes, itemType) > -1){ 
     //undefined特殊处理，object中不编码 
     if(itemType != "undefined"){ 
      resArr.push("\"" + name + "\":" + parseSimpleObject(object[name]));  
     } 
    }else{ 
     resArr.push("\"" + name + "\":" + stringify(object[name])); 
    } 
   } 
    
   return "{" + resArr.join(",") + "}"; 
  } 
 } 
  
 function parseSimpleObject(object){ 
  var type = typeof object; 
  if(type == "string" || type == "function"){ 
   return "\"" + object.toString().replace("\"", "\\\"") + "\""; 
  } 
   
  if(type == "number" || type == "boolean"){ 
   return object.toString(); 
  } 
   
  if(type == "undefined"){ 
   return "undefined"; 
  } 
   
  return "\"" + object.toString().replace("\"", "\\\"") + "\""; 
 } 
  
 function indexOf(arr, val){ 
  for(var i = 0; i < arr.length; i++){ 
   if(arr[i] === val){ 
    return i; 
   } 
  } 
   
  return -1; 
 } 
  
 /** 
  * 将stringify做二次封装 
  * @param object 要处理的对象 
  * 
  */ 
 NS.stringify = function(object, isEncodeZh){ 
  var res = stringify(object); 
  if(isEncodeZh){ 
   var encodeRes = ""; 
   for(var i = 0; i < res.length; i++){ 
    if(res.charCodeAt(i) < 0xff){ 
     encodeRes += res[i]; 
    }else{ 
     encodeRes += "\\u" + res.charCodeAt(i).toString(16); 
    } 
   } 
   res = encodeRes; 
  } 
   
  return res; 
 }; 
})(window);