js alert pop-up box appears garbled solution_javascript skills

My page is:

Copy code The code is as follows:

Calls a function in another function.php file on the page,

The code in this function is:
cho '';
I found garbled characters popping up when I accessed it with a browser.

Reason:
Because this function file does not have, is just a special function file.

Solution:

Copy code The code is as follows:

echo '< ;html>';
echo '';
echo '';
echo '';