title: Client-Side vs. Server-Side Scripts to Process Order
body: <p>I am designing a website to allow the user to pick the size of their pizza and the toppings they put on it. Based on these choices, I want to write scripts to: 
  1. calculate the cost for that pizza when the form is submitted
  2. Process payment (validate Credit Cards, etc )</p>
  
  <p>After reading countless articles, it appears obvious that I have to do all the payment processing server-side (php). For the form validaton which will determine which toppings and size the user picked and determine a price for that pizza, should I do that server side or is it better to do it client side (javascript) ? Thank you!</p>