It’s an error to report 304 without adding a timestamp. If you add a timestamp, it will be reported as 404. I don’t know what’s wrong. I’ve been struggling for a day and I really can’t. Please help me! 
ringa_lee2017-05-19 10:40:36
To add a timestamp, do you need to add it after data.json? No., otherwise it will definitely be 404
'..data.json?'+timestamp
PHPz2017-05-19 10:40:36
With parameters, add a question mark, which looks like xx.com?key=value&key1=value1
