[GitHub] [incubator-flagon-useralejs] confusingstraw commented on pull request #70: refactors var into let/const

[GitBox <gi...@apache.org>]

confusingstraw commented on pull request #70:
URL: https://github.com/apache/incubator-flagon-useralejs/pull/70#issuecomment-804985422


   ah, seems like you are right. i think it is because we only use babel in our testing, not our building.
   
   i just went down a rabbit hole trying to figure out where the hell that browser detection regex stuff i noticed in the webextension came from. turns out it was added by @poorejc , looks like it is just the inlined content of the library. this isn't relevant in this PR, especially given the change is like two years old at this point, but it is a shame we had to drop being "runtime dependency free" for that browser detection stuff.
   
   to not be entirely unhelpful, i tried to get our build system to do the `let`/`const` transformation locally, as was able to get it working with the following changes:
   
   1. add `@rollup/plugin-babel` and `@babel/plugin-transform-block-scoping` as dev dependencies
   2. update our `gulpfile.js` to include the following:
   ```js
   // near the top, with the other imports
   const {babel: rollupBabel} = require('@rollup/plugin-babel');
   
   //in the gulp.task('rollup'... plugins
           commonjs({ include: /node_modules/ }),
           rollupBabel({ babelHelpers: "runtime", exclude: /node_modules/, plugins: ["@babel/plugin-transform-block-scoping"] }),
   ```
   
   doing this seemed to result in a relatively small diff to the build outputs, and transforms any `let`/`const` usage to `var`.


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