When you want to test your PHP code, you will need a private server on your mac. The link below shows how to set up a private server on you mac.
http://coolestguidesontheplanet.com/get-apache-mysql-php-and-phpmyadmin-working-on-osx-10-11-el-capitan/
I was trying the tutorial and found I have only Javascript and html code, so that I don't need a server. I feel stupid when I experience that I'm digging in the wrong place. I appreciate my friend that helped me realise it faster. That's why I like working together!