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SurveyJS
Open-Source JSON Form Builder to Create Dynamic Forms Right in Your App. With SurveyJS form UI libraries, you can build and style forms in a fully-integrated drag & drop form builder, render them in your JS app, and store form submission data in any backend, inc. PHP, ASP.NET Core, and Node.js.
Go here: https://www.theodinproject.com make an account and do the fundamentals and all the assignments then decide from there. The Odin Project is structured very well and by the time you are done with it you will have a detailed understanding.
Next is a framework based on React. It's quite mature, quite popular, and is pretty nice to work with. You could check that out as your next thing: https://nextjs.org/
learn how to increase page performance and provide top- notch user experience. check https://web.dev.