What is this about Expanded JavaScript APIs…

What is this about?

“Expanded JavaScriptJavaScript JavaScript or JS is an object-oriented computer programming language commonly used to create interactive effects within web browsers. WordPress makes extensive use of JS for a better user experience. While PHP is executed on the server, JS executes within a user’s browser. https://www.javascript.com APIs in the customizerCustomizer Tool built into WordPress core that hooks into most modern themes. You can use it to preview and modify many of your site’s appearance settings. enable a new media experience as well as dynamic and contextual controls, sections, and panels.”