Core Viewpoint - jQuery 4.0.0 marks a significant update after nearly a decade, shedding legacy code and support for older browsers, aligning with modern front-end development needs [2][3]. Group 1 - jQuery 4.0.0 officially launched in 2026, celebrating its 20th anniversary and introducing a major version update [2]. - The update removes deprecated APIs such as jQuery.isArray and jQuery.trim, and drops support for Internet Explorer 10 and older [2]. - The development team has ensured that most users can upgrade with minimal code changes, providing an upgrade guide and migration plugins to facilitate the transition [3]. Group 2 - The new version has migrated the source code to ES modules, making it compatible with modern build tools [4]. - jQuery 4.0.0 introduces support for Trusted Types and Content Security Policy (CSP), enhancing web security [4]. - The focus event order now adheres to W3C standards, resolving previous browser compatibility issues [4]. - The compressed size of the library is reduced to 19.5k bytes, emphasizing its lightweight nature [4].