You can undo the "eject" operation of a Create React App app by adding the react-scripts package back and changing a couple of lines on the package.json file to their defaults. You can lose those /config and /scripts directories too. The only really ugly thing I found on my test (admittedly on a very simple app which is probably not at all representative of the real world) is that a number of packages were added without an easy way to get rid of. But hey, doesn't that sound like good old npm anyway?

To do this, let's assume you've done this:

Now, here's how you recover from it:

And inside the package.json file you'll need to revert the "scripts" to their former state:

I've even added the "eject" command back, for completeness.

In my test, "eject" added a few extra keys to this file: "jest", "babel", and "eslintConfig", which you can now remove as well. $ yarn start should work again.