Minification can break code (but cannot be disabled?)

In metro@0.24.7 (react-native@0.53.3), src/JSTransformer/worker/minify.js, and presumably in the latest version in metro-minify-uglify, the setting mangle:{toplevel:true} is passed to uglify-es. Unfortunately, this can break code—we have some stuff that breaks if certain React component names are mangled. Our web version uses a blacklist via mangle:{reserved}; with metro, we have to patch the transformer to stop breaking our app.

It would be great if uglify options could be configured for the transformer.

[skurgansky-sugarcrm]

@chiaraperino you can’t turn off mangle. don’t even try. try to do this:

1. yarn add -dev metro-minify-terser
2. add to metro.config.js these lines:

minifierPath: 'metro-minify-terser',
  minifierConfig: {
      // https://www.npmjs.com/package/terser#mangle-options
      ecma: 8,
      keep_classnames: true,
      keep_fnames: true,
      module: true,
      mangle: {
        module: true,
        keep_classnames: true,
        keep_fnames: true,
    }
}

worked for me. The problem was in metro-minify-uglify. it works over uglify-es when the latter works over terser.

[skurgansky-sugarcrm]

using typeorm with react-native-sqlite-storage to build offline app. As i see it minifier.js brakes my code. I have error in release but no in dev mode. When i retured _ref from minify func i didn’t have error either.