useHooks(🐠)

Easy to understand React Hook recipes by ui.dev

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Hooks are a feature in React that allow you use state and other React features without writing classes. This website provides easy to understand code examples to help you learn how hooks work and inspire you to take advantage of them in your next project.

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useOnClickOutside

This hook allows you to detect clicks outside of a specified element. In the example below we use it to close a modal when any element outside of the modal is clicked. By abstracting this logic out into a hook we can easily use it across all of our components that need this kind of functionality (dropdown menus, tooltips, etc).

import { useState, useEffect, useRef } from "react";

// Usage
function App() {
  // Create a ref that we add to the element for which we want to detect outside clicks
  const ref = useRef();
  // State for our modal
  const [isModalOpen, setModalOpen] = useState(false);
  // Call hook passing in the ref and a function to call on outside click
  useOnClickOutside(ref, () => setModalOpen(false));

  return (
    <div>
      {isModalOpen ? (
        <div ref={ref}>
          👋 Hey, I'm a modal. Click anywhere outside of me to close.
        </div>
      ) : (
        <button onClick={() => setModalOpen(true)}>Open Modal</button>
      )}
    </div>
  );
}

// Hook
function useOnClickOutside(ref, handler) {
  useEffect(
    () => {
      const listener = (event) => {
        // Do nothing if clicking ref's element or descendent elements
        if (!ref.current || ref.current.contains(event.target)) {
          return;
        }

        handler(event);
      };

      document.addEventListener("mousedown", listener);
      document.addEventListener("touchstart", listener);

      return () => {
        document.removeEventListener("mousedown", listener);
        document.removeEventListener("touchstart", listener);
      };
    },
    // Add ref and handler to effect dependencies
    // It's worth noting that because passed in handler is a new ...
    // ... function on every render that will cause this effect ...
    // ... callback/cleanup to run every render. It's not a big deal ...
    // ... but to optimize you can wrap handler in useCallback before ...
    // ... passing it into this hook.
    [ref, handler]
  );
}
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