Require.js

How the Require.js system works

It is a system that allows Javascript on the frontend to be load async
- The amount of JS that blocks render is fairly small
- And the remaining JS that's needed can be loaded at a low priority
It's also a way to manage dependencies on JS modules
- Concating every single bit of JS into one big file resolves race conditions, but means that frontend users download a TON of JS.
- Require.js gets around this by using a define(['dep']) approach, that allows dependencies to be wired in on load time.
- It's also idempotent, so that if something is already loaded, it won't load twice.
It's a way to use Javascript in a modular fashion

Sometimes the dependency tree is really long.
That means that the time to execute a specific module can be overly long if it has a series of dependencies.
AKA it takes too long.

deps
- A way to load specific JS modules on certain pages (or all) in a config
mixins
- Which let you modify behavior of existing JS objects/functions/whatever
shims
- Which let you load in non-Require.js syntax in a normal way
map
- Which lets you override existing modules in favor of whatever file you want!
text/x-magento-init, as well as data-mage-init and a whole host of other fun HTML approaches.