Handling events with React is similar to handling events on DOM elements.

• In React, event names are written in camelCase rather than lowercase.
• Additionally, in React, we can pass functions as event handlers instead of strings.

<button onClick={activateLasers}>
  Activate Lasers
</button>

• To prevent default behavior we cannot return false, we need to call preventDefault()

<button onClick={e=>e.preventDefault()}>
  Activate Lasers
</button>

The e value is a synthetic event is a synthetic event defined by React based W3C spec, you don't need to worried about cross-browser compatibility