For PHP, it makes no difference. Your PHP code isn't sent out to the browser.
For JavaScript, it is recommended that you minify your code. This reduces its size by changing variable names, removing white space, and removing all comments as well. There are several online tools for doing this, and it is often available in your IDE.
Whatever you do, leave your code commented where you work on it. Don't remove comments from PHP, and don't minify your JS by hand.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…