How create-react-app parses the umd module (import xxx from'xxx.umd.js')

[spencer17x]

I found that in create-react-app, the umd module can be parsed normally by import xxx from'./xxx.umd.js'. How is this done? Is it handled through webpack or babel? Is there a conversion from umd to esm? I did not find the source code of the relevant processing. Can you help me? thank you very much

[spencer17x]

I found out that it is supported by webpack itself...

[ubbcou]

I didn't write umdJS in the project. But when I read its example from the UMD repository, I found this (link):

    else if (typeof module === 'object' && module.exports) {
        // Node. Does not work with strict CommonJS, but
        // only CommonJS-like environments that support module.exports,
        // like Node.
        module.exports = factory(require('b'));
    }

So I can assume that the xxx.umd.js file is still treated as a js file? Module exports are normal because the standard umdjs syntax exposes module.exports

[spencer17x]

Thank you for your answers, so in fact, create-react-app does not do additional configuration, but webpack is born to handle UMD modules