Magento 2 Checkout, What should you know
Checkout in Magento 2 has been re-implemented from scratch. Now it is true single page application (SPA).
Single Page Application
Let me explain what "true" means in SPA. While user performs various interactions with Checkout functionality e.g. entering email, selecting shipping method, clicking Next button, all requests send from client's browser to a server are AJAX or asynchronous.
Server side when receiving an AJAX request processes, prepares and sends back response data to a client browser using JSON format. Checkout functionality no longer transfers chunks of rendered HTML blocks.
New Checkout is implemented as a separate application. If you expect very high volume of orders at your online website, it might be a good idea to think about running Checkout on a separate server. Unfortunately, this feature is only available for Enterprise Edition clients.
Checkout in Magento 2 is based on new UI Components which is also new. It is based on Model-View-ViewModel design pattern with support of KnockoutJS library. However it does not mean new Checkout is based on KnockoutJS, this might be false assumption. It is based on UI Components which use additional libraries including KnockoutJS, sometimes jQuery, underscore.
We no longer have to "edit core code" to introduce new functionality in Magento 2 with new Checkout. It might not be as simple and as fast as we get use to with Magento 1, however it worth trying to understand how Checkout in Magento 2 works. So we may create interesting features elegantly with backward compatibility in mind.
Videos and Articles
TOP 1 video you should have a look from Rebecca Magento Channel and 2 articles about Checkout functionality in Magento 2 written by Magento DevDocs and Inviqa.
The Magento Monthly News
Rebecca has just uploaded new video - The Magento Monthly News. You may find lots of interesting events happened during November, you may be sure there were a lot. You may also download PDF version of Magento November News.
A technical guide to the Magento 2 checkout
Inviqa team has posted detailed article about Checkout in Magento 2. The information will help you to get up to speed with frontend architecture including KnockoutJS usage, rendering and overview of UI Components usage.
Customise Checkout - Official Documentation
There is a good few examples at official Magento Documentation website about customising Checkout functionality in Magento 2. This is a must have to read before any development work!
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Keep coding, Max