{"id":5261,"date":"2025-02-26T11:24:04","date_gmt":"2025-02-26T10:24:04","guid":{"rendered":"https:\/\/www.infinity-group.pl\/blog\/?p=5261"},"modified":"2026-02-27T09:52:43","modified_gmt":"2026-02-27T08:52:43","slug":"whats-new-in-react-19","status":"publish","type":"post","link":"https:\/\/www.infinity-group.dev\/blog\/2025\/02\/26\/whats-new-in-react-19\/","title":{"rendered":"What&#8217;s New in React 19"},"content":{"rendered":"\n<p>React, one of the most widely used JavaScript libraries for building user interfaces, continues to evolve. Version 19 is among the most anticipated updates in the world of JavaScript, introducing a range of new features and improvements designed to streamline development workflows, <strong>enhance application performance, and improve user experience<\/strong>. In practical terms, React 19 brings faster page loads, more intuitive APIs, and simplified state management. This article explores the most significant changes and their impact on developers and businesses using React.<\/p><div id=\"ez-toc-container\" class=\"ez-toc-v2_0_82_2 counter-hierarchy ez-toc-counter ez-toc-light-blue ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Summary<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Prze\u0142\u0105cznik Spisu Tre\u015bci\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.infinity-group.dev\/blog\/2025\/02\/26\/whats-new-in-react-19\/#new-hooks-in-react-19\" >New hooks in React 19<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.infinity-group.dev\/blog\/2025\/02\/26\/whats-new-in-react-19\/#managing-asynchronous-operations-with-useactionstate\" >Managing asynchronous operations with useActionState<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.infinity-group.dev\/blog\/2025\/02\/26\/whats-new-in-react-19\/#optimistic-ui-updates-with-useoptimistic\" >Optimistic UI updates with useOptimistic<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.infinity-group.dev\/blog\/2025\/02\/26\/whats-new-in-react-19\/#improved-form-handling-with-useformstatus\" >Improved form handling with useFormStatus<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.infinity-group.dev\/blog\/2025\/02\/26\/whats-new-in-react-19\/#simplified-promise-handling-with-use\" >Simplified Promise handling with use<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.infinity-group.dev\/blog\/2025\/02\/26\/whats-new-in-react-19\/#introduction-of-actions\" >Introduction of Actions<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/www.infinity-group.dev\/blog\/2025\/02\/26\/whats-new-in-react-19\/#server-components\" >Server Components<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/www.infinity-group.dev\/blog\/2025\/02\/26\/whats-new-in-react-19\/#enhancements-to-hydration-and-context-apis\" >Enhancements to hydration and context APIs&nbsp;<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/www.infinity-group.dev\/blog\/2025\/02\/26\/whats-new-in-react-19\/#hydration-on-demand\" >Hydration on demand<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/www.infinity-group.dev\/blog\/2025\/02\/26\/whats-new-in-react-19\/#context-api-enhancements\" >Context API enhancements<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/www.infinity-group.dev\/blog\/2025\/02\/26\/whats-new-in-react-19\/#improved-support-for-document-metadata-and-stylesheets\" >Improved support for document metadata and stylesheets&nbsp;<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/www.infinity-group.dev\/blog\/2025\/02\/26\/whats-new-in-react-19\/#new-colour-spaces-and-css-api-enhancements\" >New colour spaces and CSS API enhancements&nbsp;<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/www.infinity-group.dev\/blog\/2025\/02\/26\/whats-new-in-react-19\/#upgrading-from-react-18-to-react-19\" >Upgrading from React 18 to React 19<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/www.infinity-group.dev\/blog\/2025\/02\/26\/whats-new-in-react-19\/#summary\" >Summary<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-15\" href=\"https:\/\/www.infinity-group.dev\/blog\/2025\/02\/26\/whats-new-in-react-19\/#contact-with-us\" >Contact with us<\/a><\/li><\/ul><\/nav><\/div>\n\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"new-hooks-in-react-19\"><\/span>New hooks in React 19<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Hooks allow developers to use state and other React features in function components without relying on classes. React 19 introduces several new hooks that <strong>simplify state management and improve code maintainability.<\/strong><\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"managing-asynchronous-operations-with-useactionstate\"><\/span>Managing asynchronous operations with useActionState<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>The useActionState hook simplifies tracking the state of asynchronous operations, such as loading and error handling, without requiring complex logic. It reduces boilerplate code, making asynchronous state management more efficient while automating error and loading state handling.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"optimistic-ui-updates-with-useoptimistic\"><\/span>Optimistic UI updates with useOptimistic<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>The useOptimistic hook facilitates optimistic UI updates by displaying UI changes immediately\u2014before receiving a server response. This is especially useful in applications with dynamic data lists, such as comments or notifications. By eliminating perceived latency, it significantly enhances the user experience.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"improved-form-handling-with-useformstatus\"><\/span>Improved form handling with useFormStatus<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>Designed specifically for forms, useFormStatus simplifies tracking submission status and error handling. It makes form validation and state management more efficient, accelerating the development process.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"simplified-promise-handling-with-use\"><\/span>Simplified Promise handling with use<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>The use hook extends the capabilities of Suspense, allowing seamless handling of Promises in functional components. It enables developers to fetch data from a context or API with minimal code, reducing the complexity of managing asynchronous operations.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"introduction-of-actions\"><\/span>Introduction of Actions<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>React 19 introduces a new mechanism called Actions, which streamlines state updates using asynchronous functions. Actions automatically manage loading and error states, support optimised updates, and provide an intuitive API for easy integration into existing applications.&nbsp;<\/p>\n\n\n\n<p>Actions can be invoked directly from components, <strong>reducing the need for intricate client-side logic.<\/strong><\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"server-components\"><\/span>Server Components<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Server Components are another groundbreaking feature in React 19, allowing portions of the UI to be rendered on the server. This leads to significant <strong>performance improvements and better SEO<\/strong>. Key benefits of Server Components include:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>reduced JavaScript bundle size,<\/li>\n<\/ul>\n\n\n\n<ul class=\"wp-block-list\">\n<li>faster page loads,<\/li>\n<\/ul>\n\n\n\n<ul class=\"wp-block-list\">\n<li>easier integration with databases and APIs.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"enhancements-to-hydration-and-context-apis\"><\/span><strong>Enhancements to hydration and context APIs<\/strong>&nbsp;<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>React 19 introduces significant enhancements to the hydration mechanism, enabling applications to load more efficiently. Optimised hydration strategies reduce interface initialisation time, leading to faster interactions and an improved user experience.&nbsp;<\/p>\n\n\n\n<p>Additionally, the updated Context API provides more precise state management, minimising unnecessary re-renders. This allows developers to fine-tune component updates, resulting in better performance and a more streamlined application architecture.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"hydration-on-demand\"><\/span>Hydration on demand<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>Traditional hydration in React requires rendering the entire component tree on the client side, which can lead to slow interactions in large applications. React 19 introduces incremental hydration, allowing only necessary interface elements to load initially. This speeds up access to essential features and improves responsiveness.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"context-api-enhancements\"><\/span>Context API enhancements<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>The updated Context API in React 19 enables more granular control over context values, allowing developers to fine-tune state management and optimise performance.&nbsp;Developers can now specify precisely which components should update when context values change, leading to better performance and cleaner, more modular code.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"improved-support-for-document-metadata-and-stylesheets\"><\/span>Improved support for document metadata and stylesheets&nbsp;<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>React 19 enhances management of document metadata, such as page titles, meta tags, and accessibility attributes. These can now be defined directly within components,<strong> streamlining dynamic content updates.<\/strong>&nbsp;<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"new-colour-spaces-and-css-api-enhancements\"><\/span>New colour spaces and CSS API enhancements&nbsp;<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>React 19 introduces support for advanced colour spaces such as LCH and Lab, enabling more natural gradient transitions and improved colour accuracy, particularly on high-resolution displays.<\/p>\n\n\n\n<p>Additionally, enhancements to the CSS API simplify integration with external stylesheets and streamline style management within components. These improvements are especially beneficial for applications with complex visual structures, where precise colour rendering and smooth transitions are essential for a polished user experience.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"upgrading-from-react-18-to-react-19\"><\/span><strong>Upgrading from React 18 to React 19<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>The transition from React 18 to React 19 is designed to be straightforward, <strong>with most applications requiring minimal code modifications<\/strong>. To ensure a smooth upgrade, consider the following steps:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Check external library compatibility: ensure that all dependencies are compatible with React 19.<\/li>\n<\/ul>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Update developer tools: tools like React Developer Tools may need updates to support the latest features.<\/li>\n<\/ul>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Test Server Components: when implementing Server Components, assess their impact on performance and application architecture.<\/li>\n<\/ul>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Leverage new hooks: hooks like useActionState and useOptimistic simplify state management but require an understanding of their usage. Reviewing the documentation and testing them in components before full integration is recommended.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"summary\"><\/span><strong>Summary<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>React 19 marks another significant step toward building more efficient, flexible, and intuitive applications. With features like new hooks, Server Components, and hydration optimisations, developers gain greater control over code structure and performance.<\/p>\n\n\n\n<p>For those planning to upgrade, verifying library compatibility, updating tools, and testing key features will ensure a smooth transition while maximising the benefits of React 19.<\/p>\n\n\n\n<p>At Infinity Group, we leverage cutting-edge technologies like React to build robust and scalable applications. If you are interested in how we can incorporate React into your next project, <strong>reach out via the form below.<\/strong><\/p>\n\n\n\n<div class=\"wp-block-contact-form-7-contact-form-selector\">\n<div class=\"wpcf7 no-js\" id=\"wpcf7-f5799-o1\" lang=\"pl-PL\" dir=\"ltr\" data-wpcf7-id=\"5799\">\n<div class=\"screen-reader-response\"><p role=\"status\" aria-live=\"polite\" aria-atomic=\"true\"><\/p> <ul><\/ul><\/div>\n<form action=\"\/blog\/wp-json\/wp\/v2\/posts\/5261#wpcf7-f5799-o1\" method=\"post\" class=\"wpcf7-form init\" aria-label=\"Formularz kontaktowy\" novalidate=\"novalidate\" data-status=\"init\">\n<fieldset class=\"hidden-fields-container\"><input type=\"hidden\" name=\"_wpcf7\" value=\"5799\" \/><input type=\"hidden\" name=\"_wpcf7_version\" value=\"6.1.5\" \/><input type=\"hidden\" name=\"_wpcf7_locale\" value=\"pl_PL\" \/><input type=\"hidden\" name=\"_wpcf7_unit_tag\" value=\"wpcf7-f5799-o1\" \/><input type=\"hidden\" name=\"_wpcf7_container_post\" value=\"0\" \/><input type=\"hidden\" name=\"_wpcf7_posted_data_hash\" value=\"\" \/><input type=\"hidden\" name=\"_wpcf7_recaptcha_response\" value=\"\" \/>\n<\/fieldset>\n<h2 class=\"form-title\"><span class=\"ez-toc-section\" id=\"contact-with-us\"><\/span>Contact with us\n<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<div class=\"form-row\">\n\t<div class=\"form-column\">\n\t\t<p><span class=\"wpcf7-form-control-wrap\" data-name=\"your-name\"><input size=\"40\" maxlength=\"400\" class=\"wpcf7-form-control wpcf7-text wpcf7-validates-as-required\" aria-required=\"true\" aria-invalid=\"false\" placeholder=\"Name and surname*\" value=\"\" type=\"text\" name=\"your-name\" \/><\/span>\n\t\t<\/p>\n\t<\/div>\n\t<div class=\"form-column\">\n\t\t<p><span class=\"wpcf7-form-control-wrap\" data-name=\"your-company\"><input size=\"40\" maxlength=\"400\" class=\"wpcf7-form-control wpcf7-text wpcf7-validates-as-required\" aria-required=\"true\" aria-invalid=\"false\" placeholder=\"Company*\" value=\"\" type=\"text\" name=\"your-company\" \/><\/span>\n\t\t<\/p>\n\t<\/div>\n<\/div>\n<div class=\"form-row\">\n\t<div class=\"form-column\">\n\t\t<p><span class=\"wpcf7-form-control-wrap\" data-name=\"your-email\"><input size=\"40\" maxlength=\"400\" class=\"wpcf7-form-control wpcf7-email wpcf7-validates-as-required wpcf7-text wpcf7-validates-as-email\" aria-required=\"true\" aria-invalid=\"false\" placeholder=\"E-mail*\" value=\"\" type=\"email\" name=\"your-email\" \/><\/span>\n\t\t<\/p>\n\t<\/div>\n\t<div class=\"form-column\">\n\t\t<p><span class=\"wpcf7-form-control-wrap\" data-name=\"phone-number\"><input size=\"40\" maxlength=\"15\" class=\"wpcf7-form-control wpcf7-tel wpcf7-text wpcf7-validates-as-tel\" aria-invalid=\"false\" placeholder=\"Phone number\" value=\"\" type=\"tel\" name=\"phone-number\" \/><\/span>\n\t\t<\/p>\n\t<\/div>\n<\/div>\n<p><span class=\"wpcf7-form-control-wrap\" data-name=\"your-message\"><textarea cols=\"40\" rows=\"10\" maxlength=\"2000\" class=\"wpcf7-form-control wpcf7-textarea\" aria-invalid=\"false\" placeholder=\"Message\" name=\"your-message\"><\/textarea><\/span>\n<\/p>\n<p><input class=\"wpcf7-form-control wpcf7-submit has-spinner\" type=\"submit\" value=\"Submit\" \/>\n<\/p>\n<div class=\"wpcf7-response-output\" aria-hidden=\"true\"><\/div>\n<p>*Required\n<\/p>\n<p class=\"klauzula-naglowek\">Clause:\n<\/p>\n<p>The administrator of your personal data is Infinity Group Sp. z o.o., with its registered office in Bia\u0142ystok.<br \/>\nThe data provided in the form will be processed for the purpose of responding to your inquiry (Article 6(1)(f) of the GDPR \u2013 the administrator\u2019s legitimate interest consisting in conducting correspondence). Providing your data is voluntary, but necessary in order to receive a response.<br \/>\nYou have, among others, the right to object to the processing of your data and the right to lodge a complaint with the President of the Personal Data Protection Office (Poland). Detailed information, including information on data recipients, the data retention period, and possible transfers of data outside the EEA, can be found under the link \u201cInformation on the processing of your personal data\u201d.\n<\/p>\n<\/form>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>React, one of the most widely used JavaScript libraries for building user interfaces, continues to evolve. Version 19 is among the most anticipated updates in the world of JavaScript, introducing a range of new features and improvements designed to streamline development workflows, enhance application performance, and improve user experience. In practical terms, React 19 brings&#8230;<\/p>\n","protected":false},"author":37,"featured_media":5792,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"class_list":["post-5261","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-web-development-en"],"_links":{"self":[{"href":"https:\/\/www.infinity-group.pl\/blog\/wp-json\/wp\/v2\/posts\/5261","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.infinity-group.pl\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.infinity-group.pl\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.infinity-group.pl\/blog\/wp-json\/wp\/v2\/users\/37"}],"replies":[{"embeddable":true,"href":"https:\/\/www.infinity-group.pl\/blog\/wp-json\/wp\/v2\/comments?post=5261"}],"version-history":[{"count":4,"href":"https:\/\/www.infinity-group.pl\/blog\/wp-json\/wp\/v2\/posts\/5261\/revisions"}],"predecessor-version":[{"id":5924,"href":"https:\/\/www.infinity-group.pl\/blog\/wp-json\/wp\/v2\/posts\/5261\/revisions\/5924"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.infinity-group.pl\/blog\/wp-json\/wp\/v2\/media\/5792"}],"wp:attachment":[{"href":"https:\/\/www.infinity-group.pl\/blog\/wp-json\/wp\/v2\/media?parent=5261"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}