I saw this little thing called icecoder on the Internet. It is a web-based editor and it is very good. The only disadvantage is that the Chinese characters in the opened file will become garbled.
After checking the source code, in lib/file-control.php, line 89 is:
echo '<script>';</span></p>
<p>It turns out that htmlentities will turn Chinese characters into garbled characters and replace them with htmlspecialchars with similar functions: <br><span>echo '</script>