Support for .mjs files added in #3239 did not account for npm libraries which ship native mjs files alongside js files. This accounts for this by ensuring .js files resolve before their accompanying .mjs file. Note that this is not an ideal end state since selecting a .mjs over a .js extension should be the result of whether `import` was used instead of `require()` in a node environment with native ESM support (currently via `--experimental-modules`). Instead, this change just *always* selects a .js extension before the .mjs extension if it exists.

This unbreaks support for using GraphQL (relay, apollo, etc) within create-react-app projects.

* Add warning when HOST environment variable is set (#3719)

* Improve HOST environment variable warning message

* Adjust text and message

Closes #3719

the code got updated from `detect()` to `choosePort` while the comment did not.

* improve eject message

* cross os implementation

* File headers BSD+Patents -> MIT

* BSD+Patents -> MIT

* rerun prettier for all files

* pin prettier to 1.6.1

* Move the reduction of the messages to a single place in the place it is used.

* Fix variable name

* format UglifyJs error

* move formatBuildError to react-dev-utils

* fix readme

* use regex for plucking the path from stack

* make path human readable and fallback to show error if regex not matched

* rename to printBuildError and add link to the docs

* fix link indentation

* improve readibility + shorten link

Jest's default value for this option is ["js", "json", "jsx", "node"].
CRA's current value is ["web.js", "js", "json", "web.jsx", "jsx"], which
is missing one of default ones: "node". This change fixes that.

This "node" extension is used in packages that use native code.

* Better React Native Web support

* Adding better react-native-web support for jest testing

* Put react-scripts in dependencies, not devDependencies

* Sort dependencies on eject

* Remove CI check

* Fix incorrect check if CI variable is set to true

Originally build would fail on warnings with any value of CI environment variable. Now it will correctly check if it's true.

Discussed here: https://github.com/facebookincubator/create-react-app/issues/2453

* Check for "not false" instead of "not true"

After discussion we decided that this will be closer to current functionality and not break anything.

* Print file sizes with correct build folder path.

* Just use the print the basename.

* Remove unnecessary dependencies(#751)

* Sort alphabetically

* Ejecting should ensure you have clean git status

* Rename function

* Style

* Minor changes

- extract function
- exclude error output for missing git
- more descriptive error message
- no need to mutate answer
- fix answering "no" to return 0 exit code

* Show warnings for builds

* Move WebpackDevServer helpers into react-dev-utils

* Override Jest config collectCoverageFrom with package.json

* Protect against overriding other options

* Better error message

* Create Jest config early on eject

* Tweak wording

* Dry it up

* Only run tests in <rootDir>/src (#544)

* updates Jest to 19.0.2

* removes testPathIgnorePatterns from jest config

* adds testMatch to jest config to only match files in src

* Bump babel-jest to 19.0.0 to match jest 19.0.2

* Upgrade to Jest 19

* Use testMatch

* Correct version

* Show network address on start

* Tweak visual representation