rollup vs esbuild: iife is not umd

Back in the day, before native ES Modules, UMD builds were superior to IIFE because we could unit test them.

And while Rollup and Webpack can produce UMD, esbuild can only make IIFE, so that was an argument against using the esbuild.

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For npm package developers (like me) it was a huge deal.

Now, in ESM world, IIFE is just as good. You can’t import neither UMD nor IIFE builds of the npm package and so, you can’t unit test them.

¯\_(ツ)_/¯