{"id":77,"date":"2025-01-22T04:47:47","date_gmt":"2025-01-22T04:47:47","guid":{"rendered":"https:\/\/techkubo.com\/react\/?p=77"},"modified":"2025-05-19T09:45:07","modified_gmt":"2025-05-19T09:45:07","slug":"react-memo","status":"publish","type":"post","link":"https:\/\/techkubo.com\/react\/react-memo\/","title":{"rendered":"React Memo"},"content":{"rendered":"\n

Utilizing React.memo<\/code> helps optimize performance by skipping the re-rendering of a component if its props have not changed.<\/p>\n\n\n\n

By avoiding unnecessary re-renders, React.memo<\/code> can boost your application’s performance.<\/p>\n\n\n\n

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

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

Consider this example where the TaskList<\/code> component re-renders even if the tasks haven’t changed.<\/p>\n\n\n\n

index.js:<\/h4>\n\n\n\n
import { useState } from "react";\nimport ReactDOM from "react-dom\/client";\nimport TaskList from ".\/TaskList";\n\nconst App = () => {\n  const [counter, setCounter] = useState(0);\n  const [tasks, setTasks] = useState(["task 1", "task 2"]);\n\n  const incrementCounter = () => {\n    setCounter((prevCounter) => prevCounter + 1);\n  };\n\n  return (\n    <>\n      <TaskList tasks={tasks} \/>\n      <hr \/>\n      <div>\n        Counter: {counter}\n        <button onClick={incrementCounter}>+<\/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
In this setup, clicking the increment button triggers a re-render of the TaskList<\/code> component, even though the tasks haven’t changed. If this component were more complex, it could negatively affect performance.<\/p>\n\n\n\n
const TaskList = ({ tasks }) => {\n  console.log("child render");\n  return (\n    <>\n      <h2>Task List<\/h2>\n      {tasks.map((task, idx) => (\n        <p key={idx}>{task}<\/p>\n      ))}\n    <\/>\n  );\n};\n\nexport default TaskList;<\/pre><\/div>\n\n\n\n
<\/p>\n\n\n\n
Solution<\/h2>\n\n\n\n
To resolve this issue, we can use React.memo<\/code>. Wrapping the TaskList<\/code> component in React.memo<\/code> prevents unnecessary re-renders.<\/p>\n\n\n\n
index.js<\/h4>\n\n\n\n
import { useState } from "react";\nimport ReactDOM from "react-dom\/client";\nimport TaskList from ".\/TaskList";\n\nconst App = () => {\n  const [counter, setCounter] = useState(0);\n  const [tasks, setTasks] = useState(["task 1", "task 2"]);\n\n  const incrementCounter = () => {\n    setCounter((prevCounter) => prevCounter + 1);\n  };\n\n  return (\n    <>\n      <TaskList tasks={tasks} \/>\n      <hr \/>\n      <div>\n        Counter: {counter}\n        <button onClick={incrementCounter}>+<\/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
import { memo } from "react";\n\nconst TaskList = ({ tasks }) => {\n  console.log("child render");\n  return (\n    <>\n      <h2>Task List<\/h2>\n      {tasks.map((task, idx) => (\n        <p key={idx}>{task}<\/p>\n      ))}\n    <\/>\n  );\n};\n\nexport default memo(TaskList);<\/pre><\/div>\n","protected":false},"excerpt":{"rendered":"
Utilizing React.memo helps optimize performance by skipping the re-rendering of a component if its props have not changed. By avoiding […]<\/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-77","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"yoast_head":"\nReact Memo - 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-memo\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"React Memo - React Tutorial\" \/>\n<meta property=\"og:description\" content=\"Utilizing React.memo helps optimize performance by skipping the re-rendering of a component if its props have not changed. 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