Uglify terser copy

[haggholm]

Summary

Add support for using terser. terser is a fork of uglify-es, which is not really maintained; and maintains API compatibility with uglify-es.

In order to avoid duplicating configuration like default options in metro-minify-uglify, this PR adds a parameter to metro-minify-uglify that allows passing in an alternative minifier module, and the new package metro-minify-terser calls this, passing in terser.

This is based on discussion in #230.

After earlier submitting #243, I created this alternative PR to address comments from @rafeca

Test plan

The tests are simply copied from metro-minify-uglify, since the API is and the results should be identical.

[rafeca]

This looks great! Thanks a lot!

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[DimitryDushkin]

Hey! How to use it?

[skurgansky-sugarcrm]

I would like to know too..

[DimitryDushkin]

I would like to know too..

Hey! For RN 57 this rn-cli.config.js works:

module.exports = {
    transformer: {
        minifierPath: 'metro-minify-terser'
    }
};

also
npm i -D metro-minify-terser

[skurgansky-sugarcrm]

@DimitryDushkin thanks for response ! btw in RN 0.59.1 there is new metro.config.js. should I use it to replace rn-cli.config.js ? It's a pity there was no comments in docs about that.

[radiosilence]

Hey @haggholm I'm trying to use this now and I get this error:

The reason I am trying it is due to this issue: #645

And using inbuilt terser support instead of using a custom config seemed like a better idea

> Task :app:bundleReleaseJsAndAssets
warning: the transform cache was reset.
                    Welcome to Metro!
              Fast - Scalable - Integrated


TypeError: Cannot read properties of undefined (reading 'match')
    at countLines (/Users/jc/Workspace/sbf/sbf.app.inspection/node_modules/metro/src/lib/countLines.js:17:23)
    at transformJS (/Users/jc/Workspace/sbf/sbf.app.inspection/node_modules/metro-transform-worker/src/index.js:332:20)
    at processTicksAndRejections (node:internal/process/task_queues:96:5)
    at async transformJSWithBabel (/Users/jc/Workspace/sbf/sbf.app.inspection/node_modules/metro-transform-worker/src/index.js:408:10)
    at async Object.transform (/Users/jc/Workspace/sbf/sbf.app.inspection/node_modules/metro-transform-worker/src/index.js:569:12)
info Run CLI with --verbose flag for more details.
error index.js: Cannot read properties of undefined (reading 'match').

My metro config:

module.exports = {
  transformer: {
    getTransformOptions: async () => ({
      transform: {
        experimentalImportSupport: false,
        inlineRequires: true,
      },
    }),
    minifierPath: "metro-minify-terser",
  },
};

[geraintwhite]

@radiosilence did you figure out a workaround for this?

[robhogan]

If you're seeing Cannot read properties of undefined (reading 'match')., be sure to use a version of metro-minify-terser that matches your metro version. See #767.

[geraintwhite]

Thanks, I suppose installing a newer version of metro doesn't work as it's tied to the react-native version (my package.json has metro, metro-minify-terser and metro-react-native-babel-preset at 0.70.1).

[robhogan]

Yes - manually adding metro to your project dependencies probably won't behave as you want, and isn't recommended - when you use the CLI you'll be using the version deep in your dependencies:

react-native -> @react-native-community/cli -> @react-native-community/cli-plugin-metro -> metro

If you're using Yarn you could (via resolutions) force @react-native-community/cli-plugin-metro onto a different version of metro, and that should work, but I haven't tried it and it's in no sense supported.

React Native 0.68 will give you Metro 0.67 which includes the latest minifier-related updates, so updating to that is another option. Otherwise, you'll need to downgrade metro-minify-terser to 0.66.

(This confusion should be sorted out soon-ish - I'm waiting for terser to cut a new release after terser/terser#1164, then we'll make metro-minify-terser the pre-bundled Metro default.)