function getItem(key) {
    	var data = WIN[STORE].getItem(STORENAME),
    	    result = new RegExp('(?:^|; )' + encode(key) + '=([^,;]*),expire=([0-9]*)').exec(data);

    	if(result && +result[2] >= +new Date) {
    		return decode(result[1]);
    	} else {
    		deleteItem(key);
    		return null;
    	}
    }
get value
@param  {String} key  the key
@return {Null}        null