metro/packages
James Ide 0f3d7117d4 Add an option to enable/disable .babelrc lookup
Summary:
By default, when Babel transforms a file, it looks for .babelrc in the file's directory and all parent directories until it finds a .babelrc file. This means that when Metro tries to transform `<PROJECT_ROOT>/node_modules/dep/mod.js`, it searches for `<PROJECT_ROOT>/node_modules/dep/.babelrc`. If that .babelrc actually exists, Babel will try to apply it.

In practice, this often causes problems because packages that include .babelrc often do so unintentionally -- they don't intend for the package consumer to look at that .babelrc file. One thing we've done a lot is `rm` all .babelrc files under node_modules -- this commit effectively achieves the same in a less destructive way by telling Babel not to look up .babelrc files. (To clarify, Metro will still apply the .babelrc file in the project root.)

Since the current behavior is to look at .babelrc files, this commit keeps that behavior for now. We'll consider overriding the default behavior (that is, making Babel not lookup .babelrc files) in the default configuration of Expo/RN projects. If this goes well and we empirically find that people are having a better time, we may want to consider flipping this option's default in Metro, so that Metro tells Babel not to look up .babelrc files by default.
Closes https://github.com/facebook/metro-bundler/pull/31

Differential Revision: D5469620

Pulled By: jeanlauliac

fbshipit-source-id: fe7a1042feafff843e1a6d8cc9487eb6ff8e8358
2017-07-24 13:43:26 -07:00
..
metro-bundler Add an option to enable/disable .babelrc lookup 2017-07-24 13:43:26 -07:00