--- title: How to Prepare for React Interviews – Front-End... description: A polyfill is a custom implementation of native JavaScript functions. The.map() polyfill method takes in a callback that gets executed inside the myMap body.... canonical: https://daily.dev/posts/how-to-prepare-for-react-interviews-front-end-technical-interview-guide-ez0ekqd4i twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: How to Prepare for React Interviews – Front-End Technical Interview Guide | daily.dev og:description: A polyfill is a custom implementation of native JavaScript functions. The.map() polyfill method takes in a callback that gets executed inside the myMap body.... og:url: https://daily.dev/posts/how-to-prepare-for-react-interviews-front-end-technical-interview-guide-ez0ekqd4i og:image: https://api.daily.dev/og/posts/Ez0EkQd4I.png og:image:alt: How to Prepare for React Interviews – Front-End Technical Interview Guide og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # How to Prepare for React Interviews – Front-End Technical Interview Guide **[freeCodeCamp](https://daily.dev/sources/freecodecamp)** · [@manuarora](https://daily.dev/manuarora) · 13 min read · 369 upvotes · 40 comments ## Summary A polyfill is a custom implementation of native JavaScript functions. The.map() polyfill method takes in a callback that gets executed inside the myMap body. This is nothing but the length of the array through which theMyMap function is called. Since map() returns a new array, we create an empty array and push the results into it. In order to implement debouncing, let's take an example. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Community discussion Top comments from developers on daily.dev. **@trungpq163** · 1 upvotes > Thanks, Many. It's very helpful **@bevisdev** · 1 upvotes > sorry, i want to ask for an example reduce why output is 57. i think 58 **@star\_knight\_\_\_** · 1 upvotes > Amazing **@logan31820** · 1 upvotes > Great blog, very simply explained every basic React hooks **@mobikhan** · 1 upvotes > can i get this in the pdf format its so helpful ## Similar posts on daily.dev - [Don’t just attend KubeCon \+ CloudNativeCon, Merge Forward your experience\!](https://daily.dev/posts/don-t-just-attend-kubecon-cloudnativecon-merge-forward-your-experience--l0rpp73x8) · CNCF · 1 upvotes · 0 comments - [Announcing H2 2026 KCDs](https://daily.dev/posts/announcing-h2-2026-kcds-m96goajm1) · CNCF · 1 upvotes · 0 comments - [Two months of Open Community Groups](https://daily.dev/posts/two-months-of-open-community-groups-asf52zhbs) · CNCF · 0 upvotes · 0 comments - [CNCF Unveils Schedule for KubeCon \+ CloudNativeCon Europe 2026](https://daily.dev/posts/cncf-unveils-schedule-for-kubecon-cloudnativecon-europe-2026-ikhcoa5cb) · CNCF · 2 upvotes · 0 comments - [CNCF Debuts KubeCon \+ CloudNativeCon Japan 2026 Schedule](https://daily.dev/posts/cncf-debuts-kubecon-cloudnativecon-japan-2026-schedule-xp5pyudub) · CNCF · 1 upvotes · 0 comments --- Tags: [#react](https://daily.dev/tags/react), [#javascript](https://daily.dev/tags/javascript), [#storage](https://daily.dev/tags/storage), [#interview](https://daily.dev/tags/interview), [#react-hooks](https://daily.dev/tags/react-hooks), [#interview-questions](https://daily.dev/tags/interview-questions) [View this post on daily.dev](https://daily.dev/posts/how-to-prepare-for-react-interviews-front-end-technical-interview-guide-ez0ekqd4i) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"How to Prepare for React Interviews – Front-End Technical Interview Guide","url":"https://daily.dev/posts/how-to-prepare-for-react-interviews-front-end-technical-interview-guide-ez0ekqd4i","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/how-to-prepare-for-react-interviews-front-end-technical-interview-guide-ez0ekqd4i"},"datePublished":"2022-09-08T02:59:12.416Z","dateModified":"2022-09-08T02:59:12.343Z","description":"A polyfill is a custom implementation of native JavaScript functions. The.map() polyfill method takes in a callback that gets executed inside the myMap body....","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/bba104cfc4fc99d01ee3fac5c62a7fd7","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/bba104cfc4fc99d01ee3fac5c62a7fd7","isAccessibleForFree":true,"articleSection":"freeCodeCamp","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Person","name":"Manu Arora","url":"https://daily.dev/manuarora","image":"https://avatars.githubusercontent.com/u/23276437?v=4","description":"Full-stack developer trying to build web apps that impacts millions of lives","interactionStatistic":{"@type":"InteractionCounter","interactionType":{"@type":"EndorseAction"},"userInteractionCount":370}},"commentCount":40,"discussionUrl":"https://daily.dev/posts/how-to-prepare-for-react-interviews-front-end-technical-interview-guide-ez0ekqd4i","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":369},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":40}],"keywords":"react,javascript,storage,interview,react-hooks,interview-questions","timeRequired":"PT13M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"freeCodeCamp","item":"https://daily.dev/sources/freecodecamp"},{"@type":"ListItem","position":3,"name":"How to Prepare for React Interviews – Front-End Technical Interview Guide"}]} {"@context":"https://schema.org","@type":"WebPage","@id":"https://daily.dev/posts/how-to-prepare-for-react-interviews-front-end-technical-interview-guide-ez0ekqd4i","comment":[{"@type":"Comment","text":"Thanks, Many. It’s very helpful","datePublished":"2022-09-09T02:53:50.735Z","dateModified":"2022-09-09T02:54:37.959Z","url":"https://daily.dev/posts/Ez0EkQd4I#c-OoYf2Nasu","author":{"@type":"Person","name":"Trung Phan","url":"https://daily.dev/trungpq163","image":"https://avatars.githubusercontent.com/u/43474427?v=4"},"interactionStatistic":{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":1}},{"@type":"Comment","text":"sorry, i want to ask for an example reduce why output is 57. i think 58","datePublished":"2022-09-13T14:46:42.564Z","url":"https://daily.dev/posts/Ez0EkQd4I#c-5rNsARePZ","author":{"@type":"Person","name":"Not Bevis","url":"https://daily.dev/bevisdev","image":"https://avatars.githubusercontent.com/u/99348676?v=4"},"interactionStatistic":{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":1}},{"@type":"Comment","text":"Amazing","datePublished":"2022-09-08T04:42:43.973Z","url":"https://daily.dev/posts/Ez0EkQd4I#c-PYXdT2ODD","author":{"@type":"Person","name":"StarKnight","url":"https://daily.dev/star_knight___","image":"https://avatars.githubusercontent.com/u/92244026?v=4"},"interactionStatistic":{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":1}},{"@type":"Comment","text":"Great blog, very simply explained every basic React hooks","datePublished":"2022-09-08T16:53:27.253Z","url":"https://daily.dev/posts/Ez0EkQd4I#c-sB44VQ4FH","author":{"@type":"Person","name":"Shaikh Mohd Noman","url":"https://daily.dev/logan31820","image":"https://lh3.googleusercontent.com/a-/AOh14Gg0Plm3eMtv5jY_hUcjKPUzOs8Wy3KjqS-P8Ljk1Q=s100"},"interactionStatistic":{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":1}},{"@type":"Comment","text":"can i get this in the pdf format its so helpful","datePublished":"2022-09-14T14:52:07.141Z","url":"https://daily.dev/posts/Ez0EkQd4I#c-1SPkCvIw4","author":{"@type":"Person","name":"YaGa BoY","url":"https://daily.dev/mobikhan","image":"https://lh3.googleusercontent.com/a-/AOh14GjMlgVJum7M3-US2ryE7HsP7XfdlY9EBzGUflbXtkU=s100"},"interactionStatistic":{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":1}}]} ```