{"id":341443,"date":"2022-06-28T10:28:53","date_gmt":"2022-06-28T10:28:53","guid":{"rendered":"https:\/\/webkul.com\/blog\/?p=341443"},"modified":"2022-06-28T10:29:02","modified_gmt":"2022-06-28T10:29:02","slug":"use-of-usememo-hook-react","status":"publish","type":"post","link":"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/","title":{"rendered":"Use of useMemo – Hook | React"},"content":{"rendered":"\n

Hello,<\/p>\n\n\n\n

In this post, we will learn the use of useMemo<\/strong> <\/a>Hook in React JS.<\/p>\n\n\n\n

The purpose of useMemo hook<\/strong> is to memoize the output of a function, It means that it executes some function and remembers the output of that function. The useMemo hook is used to improve performance in our React application.<\/p>\n\n\n\n

Syntax :<\/strong><\/p>\n\n\n\n

const memoizedValue = useMemo(functionThatReturnsValue, arrayDepencies)<\/pre>\n\n\n\n
The React useMemo<\/strong> hook accepts two parameters. These parameters are some functions whose output you want to memorize and an array of dependencies.\u00a0<\/p>\n\n\n\n
The important part comes when your component re-renders<\/strong>. After re-render, any function in the component would be normally created. If you are also calling the function, it would be also executed again. <\/p><\/blockquote>\n\n\n\n
The useMemo hook<\/strong> helps you avoid this. It allows you to execute the memoized function only under specific conditions. When these conditions are not met, the useMemo <\/strong>will not execute the function. Instead, it will return the value from the last execution. <\/p><\/blockquote>\n\n\n\n
Let’s take a small example to understand<\/strong><\/p>\n\n\n\n
We have a component that does two things – Square a number and Increases the counter.<\/p>\n\n\n\n
import React, { useState, useMemo } from "react";\n\nconst index = () => {\n  const [number, setNumber] = useState(0);\n\n  \/\/ Using useMemo\n  const squaredNum = useMemo(() => {\n    return squareNum(number);\n  }, [number]);\n  \n  const [counter, setCounter] = useState(0);\n\n  \/\/ Change the state to the input\n  const onChangeHandler = (e) => {\n    setNumber(e.target.value);\n  };\n\n  \/\/ Increases the counter by 1\n  const counterHander = () => {\n    setCounter(counter + 1);\n  };\n  return (\n    <>\n      <div className="App">\n        <h1>UseMemo- Hook<\/h1>\n        <input\n          type="number"\n          placeholder="Enter a number"\n          value={number}\n          onChange={onChangeHandler}\n        ><\/input>\n\n        <div>OUTPUT: {squaredNum}<\/div>\n        <button onClick={counterHander}>Counter ++<\/button>\n        <div>Counter : {counter}<\/div>\n      <\/div>\n    <\/>\n  );\n  \/\/ function to square the value\n    function squareNum(number) {\n        console.log("Squaring will be done!");\n        return Math.pow(number, 2);\n    }\n};\n\n\n\nexport default index;<\/pre>\n\n\n\n
In the above example,<\/strong> useMemo runs only after the initial render.  Here the function that returns the value i.e squareNum<\/strong> is passed inside the useMemo and inside the array dependencies, we have used the number as the squareNum<\/strong> will run only when the number changes. <\/p>\n\n\n\n
If we increase the counter and the number remains the same in the input field the squareNum doesn\u2019t run again. <\/p>\n\n\n\n
Let\u2019s see the output below.<\/strong><\/p>\n\n\n\n
\"Screenshot-from-2022-06-28-15-31-42\"<\/figure>\n\n\n\n
This is a small example to understand the useMemo Hook in React<\/strong>.<\/p>\n\n\n\n
Check out our blog How to Create Next App<\/a><\/p>\n\n\n\n
Happy Coding !!<\/p>\n","protected":false},"excerpt":{"rendered":"
Hello, In this post, we will learn the use of useMemo Hook in React JS. The purpose of useMemo hook is to memoize the output of a function, It means that it executes some function and remembers the output of that function. The useMemo hook is used to improve performance in our React application. Syntax […]<\/a><\/p>\n","protected":false},"author":378,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6357],"tags":[12876,12572,7895,12877,12875],"class_list":["post-341443","post","type-post","status-publish","format-standard","hentry","category-react-js","tag-hooks","tag-next-js","tag-react","tag-usememo","tag-usememo-hook"],"yoast_head":"\nUse of useMemo - Hook | React - Webkul Blog<\/title>\n<meta name=\"description\" content=\"The purpose of useMemo hook is to memoize the output of a function, It means that it executes some function and remembers the output.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Use of useMemo - Hook | React - Webkul Blog\" \/>\n<meta property=\"og:description\" content=\"The purpose of useMemo hook is to memoize the output of a function, It means that it executes some function and remembers the output.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/\" \/>\n<meta property=\"og:site_name\" content=\"Webkul Blog\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/webkul\/\" \/>\n<meta property=\"article:published_time\" content=\"2022-06-28T10:28:53+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2022-06-28T10:29:02+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/webkul.com\/blog\/wp-content\/uploads\/2022\/06\/Screenshot-from-2022-06-28-15-31-42-edited.png\" \/>\n<meta name=\"author\" content=\"Ashish Kumar\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@webkul\" \/>\n<meta name=\"twitter:site\" content=\"@webkul\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Ashish Kumar\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"2 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/\"},\"author\":{\"name\":\"Ashish Kumar\",\"@id\":\"https:\/\/webkul.com\/blog\/#\/schema\/person\/57d23646a58691882a6bd0baf5dadc21\"},\"headline\":\"Use of useMemo – Hook | React\",\"datePublished\":\"2022-06-28T10:28:53+00:00\",\"dateModified\":\"2022-06-28T10:29:02+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/\"},\"wordCount\":277,\"commentCount\":0,\"publisher\":{\"@id\":\"https:\/\/webkul.com\/blog\/#organization\"},\"image\":{\"@id\":\"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/webkul.com\/blog\/wp-content\/uploads\/2022\/06\/Screenshot-from-2022-06-28-15-31-42-edited.png\",\"keywords\":[\"Hooks\",\"Next.js\",\"react\",\"useMemo\",\"useMemo Hook\"],\"articleSection\":[\"react js\"],\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/#respond\"]}]},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/\",\"url\":\"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/\",\"name\":\"Use of useMemo - Hook | React - Webkul Blog\",\"isPartOf\":{\"@id\":\"https:\/\/webkul.com\/blog\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/#primaryimage\"},\"image\":{\"@id\":\"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/webkul.com\/blog\/wp-content\/uploads\/2022\/06\/Screenshot-from-2022-06-28-15-31-42-edited.png\",\"datePublished\":\"2022-06-28T10:28:53+00:00\",\"dateModified\":\"2022-06-28T10:29:02+00:00\",\"description\":\"The purpose of useMemo hook is to memoize the output of a function, It means that it executes some function and remembers the output.\",\"breadcrumb\":{\"@id\":\"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/#primaryimage\",\"url\":\"https:\/\/cdnblog.webkul.com\/blog\/wp-content\/uploads\/2022\/06\/Screenshot-from-2022-06-28-15-31-42-edited.png\",\"contentUrl\":\"https:\/\/cdnblog.webkul.com\/blog\/wp-content\/uploads\/2022\/06\/Screenshot-from-2022-06-28-15-31-42-edited.png\",\"width\":982,\"height\":614,\"caption\":\"Screenshot-from-2022-06-28-15-31-42\"},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/webkul.com\/blog\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Use of useMemo – Hook | React\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/webkul.com\/blog\/#website\",\"url\":\"https:\/\/webkul.com\/blog\/\",\"name\":\"Webkul Blog\",\"description\":\"\",\"publisher\":{\"@id\":\"https:\/\/webkul.com\/blog\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/webkul.com\/blog\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Organization\",\"@id\":\"https:\/\/webkul.com\/blog\/#organization\",\"name\":\"WebKul Software Private Limited\",\"url\":\"https:\/\/webkul.com\/blog\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/webkul.com\/blog\/#\/schema\/logo\/image\/\",\"url\":\"https:\/\/cdnblog.webkul.com\/blog\/wp-content\/uploads\/2021\/08\/webkul-logo-accent-sq.png\",\"contentUrl\":\"https:\/\/cdnblog.webkul.com\/blog\/wp-content\/uploads\/2021\/08\/webkul-logo-accent-sq.png\",\"width\":380,\"height\":380,\"caption\":\"WebKul Software Private Limited\"},\"image\":{\"@id\":\"https:\/\/webkul.com\/blog\/#\/schema\/logo\/image\/\"},\"sameAs\":[\"https:\/\/www.facebook.com\/webkul\/\",\"https:\/\/x.com\/webkul\",\"https:\/\/www.instagram.com\/webkul\/\",\"https:\/\/www.linkedin.com\/company\/webkul\",\"https:\/\/www.youtube.com\/user\/webkul\/\"]},{\"@type\":\"Person\",\"@id\":\"https:\/\/webkul.com\/blog\/#\/schema\/person\/57d23646a58691882a6bd0baf5dadc21\",\"name\":\"Ashish Kumar\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/webkul.com\/blog\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/secure.gravatar.com\/avatar\/3ade0803c37d8f9fe88d8255d0db5361c67b2bc36a6bafa1b3e8804285115c9b?s=96&d=https%3A%2F%2Fcdnblog.webkul.com%2Fblog%2Fwp-content%2Fuploads%2F2019%2F10%2Fmike.png&r=g\",\"contentUrl\":\"https:\/\/secure.gravatar.com\/avatar\/3ade0803c37d8f9fe88d8255d0db5361c67b2bc36a6bafa1b3e8804285115c9b?s=96&d=https%3A%2F%2Fcdnblog.webkul.com%2Fblog%2Fwp-content%2Fuploads%2F2019%2F10%2Fmike.png&r=g\",\"caption\":\"Ashish Kumar\"},\"url\":\"https:\/\/webkul.com\/blog\/author\/ashishkumar-mg770\/\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Use of useMemo - Hook | React - Webkul Blog","description":"The purpose of useMemo hook is to memoize the output of a function, It means that it executes some function and remembers the output.","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/","og_locale":"en_US","og_type":"article","og_title":"Use of useMemo - Hook | React - Webkul Blog","og_description":"The purpose of useMemo hook is to memoize the output of a function, It means that it executes some function and remembers the output.","og_url":"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/","og_site_name":"Webkul Blog","article_publisher":"https:\/\/www.facebook.com\/webkul\/","article_published_time":"2022-06-28T10:28:53+00:00","article_modified_time":"2022-06-28T10:29:02+00:00","og_image":[{"url":"https:\/\/webkul.com\/blog\/wp-content\/uploads\/2022\/06\/Screenshot-from-2022-06-28-15-31-42-edited.png","type":"","width":"","height":""}],"author":"Ashish Kumar","twitter_card":"summary_large_image","twitter_creator":"@webkul","twitter_site":"@webkul","twitter_misc":{"Written by":"Ashish Kumar","Est. reading time":"2 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/#article","isPartOf":{"@id":"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/"},"author":{"name":"Ashish Kumar","@id":"https:\/\/webkul.com\/blog\/#\/schema\/person\/57d23646a58691882a6bd0baf5dadc21"},"headline":"Use of useMemo – Hook | React","datePublished":"2022-06-28T10:28:53+00:00","dateModified":"2022-06-28T10:29:02+00:00","mainEntityOfPage":{"@id":"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/"},"wordCount":277,"commentCount":0,"publisher":{"@id":"https:\/\/webkul.com\/blog\/#organization"},"image":{"@id":"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/#primaryimage"},"thumbnailUrl":"https:\/\/webkul.com\/blog\/wp-content\/uploads\/2022\/06\/Screenshot-from-2022-06-28-15-31-42-edited.png","keywords":["Hooks","Next.js","react","useMemo","useMemo Hook"],"articleSection":["react js"],"inLanguage":"en-US","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/#respond"]}]},{"@type":"WebPage","@id":"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/","url":"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/","name":"Use of useMemo - Hook | React - Webkul Blog","isPartOf":{"@id":"https:\/\/webkul.com\/blog\/#website"},"primaryImageOfPage":{"@id":"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/#primaryimage"},"image":{"@id":"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/#primaryimage"},"thumbnailUrl":"https:\/\/webkul.com\/blog\/wp-content\/uploads\/2022\/06\/Screenshot-from-2022-06-28-15-31-42-edited.png","datePublished":"2022-06-28T10:28:53+00:00","dateModified":"2022-06-28T10:29:02+00:00","description":"The purpose of useMemo hook is to memoize the output of a function, It means that it executes some function and remembers the output.","breadcrumb":{"@id":"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/"]}]},{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/#primaryimage","url":"https:\/\/cdnblog.webkul.com\/blog\/wp-content\/uploads\/2022\/06\/Screenshot-from-2022-06-28-15-31-42-edited.png","contentUrl":"https:\/\/cdnblog.webkul.com\/blog\/wp-content\/uploads\/2022\/06\/Screenshot-from-2022-06-28-15-31-42-edited.png","width":982,"height":614,"caption":"Screenshot-from-2022-06-28-15-31-42"},{"@type":"BreadcrumbList","@id":"https:\/\/webkul.com\/blog\/use-of-usememo-hook-react\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/webkul.com\/blog\/"},{"@type":"ListItem","position":2,"name":"Use of useMemo – Hook | React"}]},{"@type":"WebSite","@id":"https:\/\/webkul.com\/blog\/#website","url":"https:\/\/webkul.com\/blog\/","name":"Webkul Blog","description":"","publisher":{"@id":"https:\/\/webkul.com\/blog\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/webkul.com\/blog\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/webkul.com\/blog\/#organization","name":"WebKul Software Private Limited","url":"https:\/\/webkul.com\/blog\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/webkul.com\/blog\/#\/schema\/logo\/image\/","url":"https:\/\/cdnblog.webkul.com\/blog\/wp-content\/uploads\/2021\/08\/webkul-logo-accent-sq.png","contentUrl":"https:\/\/cdnblog.webkul.com\/blog\/wp-content\/uploads\/2021\/08\/webkul-logo-accent-sq.png","width":380,"height":380,"caption":"WebKul Software Private Limited"},"image":{"@id":"https:\/\/webkul.com\/blog\/#\/schema\/logo\/image\/"},"sameAs":["https:\/\/www.facebook.com\/webkul\/","https:\/\/x.com\/webkul","https:\/\/www.instagram.com\/webkul\/","https:\/\/www.linkedin.com\/company\/webkul","https:\/\/www.youtube.com\/user\/webkul\/"]},{"@type":"Person","@id":"https:\/\/webkul.com\/blog\/#\/schema\/person\/57d23646a58691882a6bd0baf5dadc21","name":"Ashish Kumar","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/webkul.com\/blog\/#\/schema\/person\/image\/","url":"https:\/\/secure.gravatar.com\/avatar\/3ade0803c37d8f9fe88d8255d0db5361c67b2bc36a6bafa1b3e8804285115c9b?s=96&d=https%3A%2F%2Fcdnblog.webkul.com%2Fblog%2Fwp-content%2Fuploads%2F2019%2F10%2Fmike.png&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/3ade0803c37d8f9fe88d8255d0db5361c67b2bc36a6bafa1b3e8804285115c9b?s=96&d=https%3A%2F%2Fcdnblog.webkul.com%2Fblog%2Fwp-content%2Fuploads%2F2019%2F10%2Fmike.png&r=g","caption":"Ashish Kumar"},"url":"https:\/\/webkul.com\/blog\/author\/ashishkumar-mg770\/"}]}},"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/webkul.com\/blog\/wp-json\/wp\/v2\/posts\/341443","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/webkul.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/webkul.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/webkul.com\/blog\/wp-json\/wp\/v2\/users\/378"}],"replies":[{"embeddable":true,"href":"https:\/\/webkul.com\/blog\/wp-json\/wp\/v2\/comments?post=341443"}],"version-history":[{"count":2,"href":"https:\/\/webkul.com\/blog\/wp-json\/wp\/v2\/posts\/341443\/revisions"}],"predecessor-version":[{"id":341450,"href":"https:\/\/webkul.com\/blog\/wp-json\/wp\/v2\/posts\/341443\/revisions\/341450"}],"wp:attachment":[{"href":"https:\/\/webkul.com\/blog\/wp-json\/wp\/v2\/media?parent=341443"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/webkul.com\/blog\/wp-json\/wp\/v2\/categories?post=341443"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/webkul.com\/blog\/wp-json\/wp\/v2\/tags?post=341443"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}