How do I run a php script who runs a function which saves something on a .txt file without refreshing that php function?

Question

maybe an example, please?

Answer 1

Asynchronous Javascript and XML (AJAX). Have JS invoke PHP by sending information without reloading to a file > PHP then follows instructions/code accordingly.

Answer 2

$file = fopen('myfile.txt', 'a');
fwrite($file, "Some text");
fclose($file);

If you want input from form without refreshing then use ajax.