How to install typescript + jest with create-react-app? - reactjs

Question

I want to install typescript and jest in a create-react-app-based app. I feel that since this is such a common installation choice there must be at least one "everything just works" set of configuration steps to follow.
I initially ran npx create-react-app my-project --template typescript. That was great for a while. I wrote several thousand lines of code with that. And then one day I decided I wanted to add some mocks to a spec file with code like this:
import jest from "jest";
jest.mock('./somemodule');
...but the "jest" instance is undefined. So I followed directions in different articles to install further devDependencies. But these seem to conflict with dependencies inside of create-react-app, suggesting that I need to focus on setting up my project correctly the "Create-react-app Way" according to its expectations.
Rather than burden StackOverflow with the details of my build and package management issues, I figure I'll just ask the simpler question - what is the correct way to set up create-react-app+typescript+jest in a way where it doesn't have a bunch of irritating, random problems?
And then after I've followed this advice, if I still have problems, I might ask a second, separate SO question with specific details.

Answer 1

The command below should create a new React project supporting Typescript and Jest without need of further modification.
npx create-react-app my-app --template typescript
Details about the above command can be found here: https://create-react-app.dev/docs/adding-typescript/
The above command will set up a new project. But if, like me, you have an existing create-react-app project with issues like:
the Jest module is undefined or doesn't seem to have expected functions
your npm run start and npm run build fail due to conflicting dependencies
or you just want to get to a "standard" package.json configuration without all the hassle of copying your source into a new project.
...you can use the process below to fix/upgrade your package.json:
Use the same npx create-react-app my-app --template typescript command above to create a separate working ("Good") project with all the right dependencies. This project will just be used as a reference.
Compare the package.json of the Good project to the non-working ("Bad") project, and make sure the Bad package.json has the same modules and version#s as the Good package.json. You probably don't have to delete any modules in the Bad package.json that aren't in the Good package.json.
rm -rf node-modules in the Bad project.
rm package-lock.json in the Bad project.
npm install in the Bad project.
Self-answering for posterity.