{"id":113,"date":"2025-01-29T05:17:49","date_gmt":"2025-01-29T05:17:49","guid":{"rendered":"https:\/\/techkubo.com\/react\/?p=113"},"modified":"2025-05-19T10:26:40","modified_gmt":"2025-05-19T10:26:40","slug":"react-usecallback-hook","status":"publish","type":"post","link":"https:\/\/techkubo.com\/react\/react-usecallback-hook\/","title":{"rendered":"React useCallback Hook"},"content":{"rendered":"\n

The useCallback<\/code> Hook in React provides a memoized callback function. Think of memoization as a way to cache a value to avoid recalculating it. This helps isolate resource-intensive functions so they don’t run on every render.<\/p>\n\n\n\n

The useCallback<\/code> Hook only re-executes when one of its dependencies changes, which can boost performance.<\/p>\n\n\n\n

The useCallback<\/code> and useMemo<\/code> Hooks are similar. The key difference is that useMemo<\/code> returns a memoized value, while useCallback<\/code> returns a memoized function.<\/p>\n\n\n\n

<\/p>\n\n\n\n

Problem<\/h2>\n\n\n\n

A common reason to use useCallback<\/code> is to prevent a component from re-rendering unless its props change.<\/p>\n\n\n\n

In this example, you might assume the TaskList<\/code> component won’t re-render unless the tasks change.<\/p>\n\n\n\n

<\/p>\n\n\n\n

Example<\/h2>\n\n\n\n

index.js<\/h4>\n\n\n\n
\/\/ index.js\nimport { useState } from "react";\nimport ReactDOM from "react-dom\/client";\nimport TaskList from ".\/TaskList";\n\nconst App = () => {\n  const [count, setCount] = useState(0);\n  const [tasks, setTasks] = useState([]);\n\n  const increment = () => {\n    setCount((c) => c + 1);\n  };\n  const addTask = () => {\n    setTasks((t) => [...t, "New Task"]);\n  };\n\n  return (\n    <>\n      <TaskList tasks={tasks} addTask={addTask} \/>\n      <hr \/>\n      <div>\n        Count: {count}\n        <button onClick={increment}>+<\/button>\n      <\/div>\n    <\/>\n  );\n};\n\nconst root = ReactDOM.createRoot(document.getElementById('root'));\nroot.render(<App \/>);<\/pre><\/div>\n\n\n\n
TaskList.js<\/h4>\n\n\n\n
Run this and click the count increment button. You’ll notice the TaskList<\/code> component re-renders even when the tasks don’t change.<\/p>\n\n\n\n
Why doesn’t this work? Even with memo<\/code>, the TaskList<\/code> component re-renders because the tasks<\/code> state and the addTask<\/code> function remain unchanged when the count is incremented. This happens due to “referential equality”. Every time a component re-renders, its functions get recreated, meaning the addTask<\/code> function changes.<\/p>\n\n\n\n
\/\/ TaskList.js\nimport { memo } from "react";\n\nconst TaskList = ({ tasks, addTask }) => {\n  console.log("child render");\n  return (\n    <>\n      <h2>My Tasks<\/h2>\n      {tasks.map((task, index) => {\n        return <p key={index}>{task}<\/p>;\n      })}\n      <button onClick={addTask}>Add Task<\/button>\n    <\/>\n  );\n};\n\nexport default memo(TaskList);<\/pre><\/div>\n\n\n\n
<\/p>\n\n\n\n
Solution<\/h2>\n\n\n\n
To fix this, use the useCallback<\/code> Hook to prevent the function from being recreated unless necessary.<\/p>\n\n\n\n
Use useCallback<\/code> to stop the TaskList<\/code> component from re-rendering needlessly<\/p>\n\n\n\n
Example<\/h2>\n\n\n\n
index.js<\/h4>\n\n\n\n
\/\/ index.js\nimport { useState, useCallback } from "react";\nimport ReactDOM from "react-dom\/client";\nimport TaskList from ".\/TaskList";\n\nconst App = () => {\n  const [count, setCount] = useState(0);\n  const [tasks, setTasks] = useState([]);\n\n  const increment = () => {\n    setCount((c) => c + 1);\n  };\n  const addTask = useCallback(() => {\n    setTasks((t) => [...t, "New Task"]);\n  }, [tasks]);\n\n  return (\n    <>\n      <TaskList tasks={tasks} addTask={addTask} \/>\n      <hr \/>\n      <div>\n        Count: {count}\n        <button onClick={increment}>+<\/button>\n      <\/div>\n    <\/>\n  );\n};\n\nconst root = ReactDOM.createRoot(document.getElementById('root'));\nroot.render(<App \/>);<\/pre><\/div>\n\n\n\n
TaskList.js<\/h4>\n\n\n\n
Now the TaskList<\/code> component will only re-render when the tasks<\/code> prop changes.<\/p>\n\n\n\n
\/\/ TaskList.js\nimport { memo } from "react";\n\nconst TaskList = ({ tasks, addTask }) => {\n  console.log("child render");\n  return (\n    <>\n      <h2>My Tasks<\/h2>\n      {tasks.map((task, index) => {\n        return <p key={index}>{task}<\/p>;\n      })}\n      <button onClick={addTask}>Add Task<\/button>\n    <\/>\n  );\n};\n\nexport default memo(TaskList);<\/pre><\/div>\n","protected":false},"excerpt":{"rendered":"
The useCallback Hook in React provides a memoized callback function. Think of memoization as a way to cache a value […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[1],"tags":[],"class_list":["post-113","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"yoast_head":"\nReact useCallback Hook - React Tutorial<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/techkubo.com\/react\/react-usecallback-hook\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"React useCallback Hook - React Tutorial\" \/>\n<meta property=\"og:description\" content=\"The useCallback Hook in React provides a memoized callback function. 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