E-commerce Website. PHP OR Node.Js?

Node seems to be the better option because of several benefits such as high performance, possibilities and what it has to offer in the server-side. It is improving in terms of future use for projects as more companies are incorporating Node. NodeJS is also asynchronous and allows more flexibility in deployment/management of connections so the scalability is much higher. On the back-end, part of it is compiled. The language also allows for much more flexibility and runs on ES7 (modern version). If you learn javascript it would help to learn Node as you plan on making a website (front/backend).

I'm just starting off with this having learnt from Team Treehouse - I would say go with PHP as in most cases to use Node you need a dedicated server which have fixed costs and it is complicated to maintain relative to PHP, which can run on a shared server (much cheaper) and you could use plugins such as Woocommerce, or other cheap, reliable technology. If you want to make a business then PHP would get you to your goal of selling quicker.

The advantages of Node (asynchronous etc) do not seem to benefit a typical ecommerce website, where you likely will not hit that bottleneck - in my experience anyway.

Most would say PHP, I love Node JS although there is no point using a specific technology when there is perfectly aduquate tech out there for E-Commerce solutions especially for a commercial project/client try magento 2 very good solution! https://magento.com/advantage or alternatively WordPress WooCommerce.