No Access-Control-Allow-Origin header

Question

I try to get data from a database via XMLHttpRequest but I keep getting No Access-Control-Allow-Origin warning even though I have add the necessary header on the php file.
How so?
https://code.sololearn.com/WcXOnxi8WKD6/?ref=app

Answer 1

This is a CORS problem. You should be rest assured that it allowed on server side controller and also added in header of your request. For details: https://stackoverflow.com/questions/10636611/how-does-access-control-allow-origin-header-work