Mai Lam

unctional components are easier to unde…lass components. Some of these restrictions may go away in the future but they exist today. Because functional components are easier to understand, I suggest you to use them unless you need state, lifecycle hooks, or performance optimizations, which are only available to the class components at this time.

Are usually generated using higher order components such as connect() from React Redux, createContainer() from Relay, or Container.create() from Flux Utils, rather than written by hand.

iables and constants have block scope (surrounded by …eat, but don’t we have variables in JavaScript already? Yes, that’s true, but variables declared by var have function scope and are hoisted to the top. It means that a variable can be used before it has been declared. let variables and constants have block scope (surrounded by {}) and cannot be used before declaration.