JavaScript对象转换成JSON字符串及深度克隆方法

Object.prototype.deep_clone = function(){   
     eval("var tmp = " + this.toJSON());   
    return tmp;   
}   
Object.prototype.toJSON = function(){   
     var json = [];   
    for(var i in this){   
        if(!this.hasOwnProperty(i)) continue;   
        //if(typeof this[i] == "function") continue;   
         json.push(   
             i.toJSON() + " : " +   
             ((this[i] != null) ? this[i].toJSON() : "null")   
         )   
     }   
    return "{\n " + json.join(",\n ") + "\n}";   
}   
Array.prototype.toJSON = function(){   
    for(var i=0,json=[];i<this.length;i++)   
         json[i] = (this[i] != null) ? this[i].toJSON() : "null";   
    return "["+json.join(", ")+"]"  
}   
  
String.prototype.toJSON = function(){   
    return '"' +   
        this.replace(/(\\|\")/g,"\\$1")   
         .replace(/\n|\r|\t/g,function(){   
             var a = arguments[0];   
            return   (a == '\n') ? '\\n':   
                     (a == '\r') ? '\\r':   
                     (a == '\t') ? '\\t': ""  
         }) +   
        '"'  
}   
Boolean.prototype.toJSON = function(){return this}   
Function.prototype.toJSON = function(){return this}   
Number.prototype.toJSON = function(){return this}   
RegExp.prototype.toJSON = function(){return this}   
  
// strict but slow   
String.prototype.toJSON = function(){   
     var tmp = this.split("");   
    for(var i=0;i<tmp.length;i++){   
         var c = tmp[i];   
         (c >= ' ') ?   
             (c == '\\') ? (tmp[i] = '\\\\'):   
             (c == '"')   ? (tmp[i] = '\\"' ): 0 :   
         (tmp[i] =   
             (c == '\n') ? '\\n' :   
             (c == '\r') ? '\\r' :   
             (c == '\t') ? '\\t' :   
             (c == '\b') ? '\\b' :   
             (c == '\f') ? '\\f' :   
             (c = c.charCodeAt(),('\\u00' + ((c>15)?1:0)+(c%16)))   
         )   
     }   
    return '"' + tmp.join("") + '"';   
}