What JS combination of tools can you use to get similar to Flex, you would have to add a build tool, some JS framework like angular or react+friends then bootst

What JS combination of tools can you use to get similar to Flex, you would have to add a build tool, some JS framework like angular or react+friends then bootstrap or similar to get some basic widgets or pick the widgets you need from the web(ex pick a jQuery advanced calendar widget and wrap it in angular or React , I saw a lot of code that did bad such wrappings that were single use)