--- title: 3 React concepts I wish I knew when I started | daily.dev description: React uses keys to optimise performance. Keys help React identify which items have changed, are added, or are removed. In some cases you don’t have the latest... canonical: https://daily.dev/posts/3-react-concepts-i-wish-i-knew-when-i-started-plc24cv9i twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: 3 React concepts I wish I knew when I started | daily.dev og:description: React uses keys to optimise performance. Keys help React identify which items have changed, are added, or are removed. In some cases you don’t have the latest... og:url: https://daily.dev/posts/3-react-concepts-i-wish-i-knew-when-i-started-plc24cv9i og:image: https://api.daily.dev/og/posts/plC24cV9i.png og:image:alt: 3 React concepts I wish I knew when I started 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. # 3 React concepts I wish I knew when I started **[JSK](https://daily.dev/sources/jsk)** · 4 min read · 33 upvotes · 2 comments ## Summary React uses keys to optimise performance. Keys help React identify which items have changed, are added, or are removed. In some cases you don’t have the latest state at your disposal. For someone who had no idea why they were in the “the-scenes” in React, I had to read a lot to get my head around. ## 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. **@ghost** · 4 upvotes > Woah, got to know about the stale state! **@gottsito** · 1 upvotes > thanks for advice !! --- Tags: [#react](https://daily.dev/tags/react), [#javascript](https://daily.dev/tags/javascript) [View this post on daily.dev](https://daily.dev/posts/3-react-concepts-i-wish-i-knew-when-i-started-plc24cv9i) ```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":"3 React concepts I wish I knew when I started","url":"https://daily.dev/posts/3-react-concepts-i-wish-i-knew-when-i-started-plc24cv9i","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/3-react-concepts-i-wish-i-knew-when-i-started-plc24cv9i"},"datePublished":"2020-10-29T11:37:42.630Z","dateModified":"2021-10-07T14:17:10.317Z","description":"React uses keys to optimise performance. 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