Is java script necessary for php..?

Javascript is not necessary to learn PHP. JS, for me, is only to make your site more interactive. I use javascript mainly because of its "Events".

Let's say you have a form and you want the user to only enter no more than 20 characters, you'd want to put a counter so they'll know they haven't exceeded the limit. You'd use JS to show a counter beside each form element, this counter will increase by 1 each time a character is entered.

PHP is used to generate HTML and JavaScript, so it might be useful to know js, but it's not necessary. It might be worth while to learn jQuery though. It's basically a javascript library used to make javascript development much easier, and you will benefit greatly by using it.

haha. I can code in PHP and have very little knowledge of JavaScript.