When you attach an event handler function to a DOM element using the native
addEventListener() function, the callback will get an event argument passed to it. Event handler functions in React are also passed an event argument, but it's not the standard
Event instance. It's called
SyntheticEvent, and it's a simple wrapper for native event instances.
Synthetic events serve two purposes in React:
Here's an illustration of the synthetic event in the context of a React component:
In the next section, you'll see how these synthetic events are pooled ...