How to use React useCallback hook with examples

How to use React useCallback hook with examples

In this tutorial, we are going to learn about how to use react useCallback hook and advantages of using useCallback hook with examples.

useCallback() hook

The useCallback() hook helps us to memoize the functions so that it prevents the re-creating of functions on every re-render.

The function we passed to the useCallback hook is only re-created when one of its dependencies are changed.

Let’s see an example:

import React, {useState} from "react";
import ReactDOM from "react-dom";

function Button(props) {
  return <button onClick={props.onClick}>{props.name}</button>;}

function App() {
  const [count, setCount] = useState(0);
  const [isActive, setActive] = useState(false);

  const handleCount = () => setCount(count + 1);  const handleShow = () => setActive(!isActive);
  return (
    <div className="App">
      {isActive && (        <div>          <h1>{count}</h1>          <Button onClick={handleCount} name="Increment" />        </div>      )}      <Button onClick={handleShow}
        name={isActive ? "Hide Counter" : "Show Counter"}
      />
    </div>
  );
}

ReactDOM.render(<App />, document.getElementById("root"));

In the above code, we have two functions which are (handleCount, handleShow) and the problem is every time if we click on any button UI is updated and two functions are re-created again.

To solve this problem we need to wrap our functions with useCallback hook.

import React, { useState, useCallback } from "react";
import ReactDOM from "react-dom";

function Button(props) {
  return <button onClick={props.onClick}>{props.name}</button>;
}

function App() {
  const [count, setCount] = useState(0);
  const [isActive, setActive] = useState(false);

  const handleCount = useCallback(() => setCount(count + 1), [count]);  const handleShow = useCallback(() => setActive(!isActive), [isActive]);
  return (
    <div className="App">
      {isActive && (
        <div>
          <h1>{count}</h1>
          <Button onClick={handleCount} name="Increment" />
        </div>
      )}
      <Button
        onClick={handleShow}
        name={isActive ? "Hide Counter" : "Show Counter"}
      />
    </div>
  );
}

ReactDOM.render(<App />, document.getElementById("root"));

Here wrapped our two functions with useCallback hook and second argument is a dependency, so that functions are only re-created if one of its dependency value is changed.

Now, If we click on Increment button count value is changed and handleCount function is re-created.