js JSON与String互转换

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;  
        }  
    }

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