json与string互转

function stringToJSON (obj){   
        return eval('(' + obj + ')');   
}

function  jsonToString (obj){   
        var THIS = this;    
        switch(typeof(obj)){   
            case 'string':   
                return '"' + obj.replace(/(["\\])/g, '\\$1') + '"';   
            case 'array':   
                return '[' + obj.map(THIS.jsonToString).join(',') + ']';   
            case 'object':   
                 if(obj instanceof Array){   
                    var strArr = [];   
                    var len = obj.length;   
                    for(var i=0; i<len; i++){   
                        strArr.push(THIS.jsonToString(obj[i]));   
                    }   
                    return '[' + strArr.join(',') + ']';   
                }else if(obj==null){   
                    return 'null';   
   
                }else{   
                    var string = [];   
                    for (var property in obj) string.push(THIS.jsonToString(property) + ':' + THIS.jsonToString(obj[property]));   
                    return '{' + string.join(',') + '}';   
                }   
            case 'number':   
                return obj;   
            case false:   
                return obj;   
        }   
    }