Leaderboard

Since the <button> doesn't have a "type" attribute, the default behavior is to submit the form. That's likely why the page is flashing and the button is redisplayed. You could try the following: echo" <br><br><button name='submit' type='button' class = 'btn' id='btn' onclick='hideButton()'>Click to Verify Information</button>"; More information about the <button> tag can be found here: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/button With that said, I'm guessing the button is supposed to submit the form given it's named "submit". So you may need to tweak the JavaScript to submit the form if the verification process doesn't find any issues.

What does "comes back after a blink" mean? First thing I notice is that you're missing a closing brace in your function.

You will have to write a separate query to update the other table. Be sure to check the first query is successful before doing the second one. And read up on how to do a prepared query since you are inserting user-generated data into your table which could corrupt your database. And - BTW - you would be better off if you learned to use the PDO interface instead of MySqlI. If you have access to it.

*slow clap* response.ok will always be true as long as your endpoint is returning 200. If you want to use response.ok then you have to send a non-200 on failure.