How Can I Debounce User Input for Responsive Yet Efficient useEffect Triggering in React?

Question

I'm currently working on a React project that utilizes React Router with react-router-dom. In one of my components, I'm using the setSearchParams function from useSearchParams to manage and modify URL query parameters. According to my understanding, when I use setSearchParams to update the URL query parameters and return the current object reference, it should not trigger the useEffect. However, I've noticed that the useEffect is triggered even when I return the same object reference.

Why does it happen?

I have an input field that triggers an useEffect whenever the user types. While I want the input to be responsive, I also want to avoid triggering the useEffect too frequently, especially when the user is typing rapidly.

How can I accomplish that?

Here's my code:

import {
  BrowserRouter as Router,
  Route,
  Routes,
  useSearchParams,
} from 'react-router-dom';
import React, { useEffect, useRef } from 'react';
import './style.css';

const Home = () => {
  const debounce = useDebounce();

  const [searchParams, setSearchParams] = useSearchParams();

  const name = searchParams.get('name') || '';

  useEffect(() => {
    console.log('useEffect triggered');
    // i am gonna call an API here
  }, [searchParams]);

  return (
    <div>
      <div>
        <label>Name:</label>
        <input
          type="text"
          value={name}
          onChange={(e) => {
            setSearchParams(
              (prev) => {
                prev.set('name', e.target.value);
                return prev;
              },
              { replace: true }
            );
          }}
        />
      </div>
    </div>
  );
};

function useDebounce() {
  const timeout = useRef(null);
  function debounce(cb, delay = 1000) {
    return (...args) => {
      if (timeout.current) clearTimeout(timeout.current);
      timeout.current = setTimeout(() => {
        cb(...args);
      }, delay);
    };
  }
  return debounce;
}

function App() {
  return (
    <Router>
      <div>
        <nav>
          <ul>
            <li>
              <a href="/">Home</a>
            </li>
          </ul>
        </nav>
        <Routes>
          <Route path="/" element={<Home />} />
        </Routes>
      </div>
    </Router>
  );
}

export default App;

Answer 1

According to my understanding, when I use setSearchParams to update the URL query parameters and return the current object reference, it should not trigger the useEffect. However, I've noticed that the useEffect is triggered even when I return the same object reference.

Why does it happen?

I think conceptually your understanding is "correct", but the current implementation of useSearchParams doesn't return a stable searchParams object reference. There is an open GitHub issue here regarding "Make setSearchParams stable".

Some workarounds are suggested in the thread.

What this means is that using searchParams as a useEffect hook dependency will trigger the effect each render cycle.

I have an input field that triggers an useEffect whenever the user types. While I want the input to be responsive, I also want to avoid triggering the useEffect too frequently, especially when the user is typing rapidly.

How can I accomplish that?

You can't debounce React hooks. You should debounce the function that would be called too often as a side-effect.

Example debouncing a function that calls the API.

const Home = () => {
  const debounce = useDebounce();

  const [searchParams, setSearchParams] = useSearchParams();

  const name = searchParams.get("name") || "";

  // Create memoized, stable debounced callback reference
  const someApi = useCallback(debounce((name) => {
    console.log("callin some API", { name });
  }), [])

  useEffect(() => {
    console.log("useEffect triggered", { name });
    // i am gonna call an API here
    someApi(name);
  }, [someApi, name]);

  return (
    <div>
      <div>
        <label>Name:</label>
        <input
          type="text"
          value={name}
          onChange={(e) => {
            setSearchParams(
              (prev) => {
                prev.set("name", e.target.value);
                return prev;
              },
              { replace: true }
            );
          }}
        />
      </div>
    </div>
  );
};