javascript - I'm new to php and have garbled code problems.

In the article publishing system, when I submit the form, a prompt will be alerted after the submission is successful, but the Chinese characters will appear garbled.
I found some information online and there are three places where you should pay attention to character encoding.
One: header
Two: Database character encoding
Three: File saving encoding
After setting them all, it still doesn’t work.

demo:
http://www.mrchen573.com/php_...

Reply content:

In the article publishing system, when I submit the form, a prompt will be alerted after the submission is successful, but the Chinese characters will appear garbled.
I found some information online and there are three places where you should pay attention to character encoding.
One: Header
Two: Database character encoding
Three: File saving encoding
After setting them all, it still doesn’t work.

demo:
http://www.mrchen573.com/php_...

The poster directly echoes a Chinese text and reads it without using the scripttag

**Add another sentence above this echo
echo ""**