Modern JS Overview
This is not a course on Modern JS, however, it is useful to learn a few things before diving too far into the React/Gatsby code. Some of this may be review if you have worked on modern JavaScript projects. However, if you haven't, then some of this syntax is going to look strange and possibly confusing.
Don't worry if you don't fully understand the syntax yet, you will pick it up as we go through the rest of the training. If you still don't understand some of these concepts after the training is completed, you may want to do some additional research/training on modern JS until you are more familiar with the syntax.