events and state

Question 1

What is the purpose of state in React?

Answer 1

to make a component truly reusable and encapsulated

CONTROL WHAT THE COMPONENT OUTPUTS BY CONTROLLING THE STATE;
anything that needs to change over time or when user interacts state handles that

Question 2

How to you pass an event handler to a React element?

Answer 2

With JSX you pass a function as the event handler, rather than a string.

When you define a component using an ES6 class, a common pattern is for an event handler to be a method on the class