Interactivity, State, and Hooks

Using React state

At this point, React has taken over part of our page and is drawing the seats, which is nice enough, but we’d like it to, you know, react to something. We’d like to have a little interactivity.

In React, you can use JSX to specify event handlers on React elements in much the same way you would when writing old-school JavaScript embedded in HTML. The problem is how to make changes to our components as a result of those events. As mentioned, the props we pass into each component are immutable, which means if we want to change something about a component, we can’t use props.

React uses the term state to refer to the parts of a component that change and when changed trigger an update to how the component is displayed. To be clear, although a component can’t change its own props, if the state of a parent component changes, that can cause the parent to re-render a child component with new props.

Because state changes are used by React to trigger a redrawing of the page, React requires you to register them with the system; you can’t just change the value of a variable and be done with it.

React hooks

React allows you to designate a value as being part of the state and gives you a special setter for that value using a mechanism called hooks. Hooks are new in React 16.8. Before then components defined as functions could not ...