Apply Rollup Plugin by OutputOptions

npm i -D rollup-plugin-by-output

// rollup.config.js
import babel from 'rollup-plugin-babel';
import terser from 'rollup-plugin-terser';
import plugins, {file} from 'rollup-plugin-by-output';
export default {
  // ...
  plugins: plugins(babel(), [file(pkg.browser), terser()]),
  output: [
    {
      globals: {
        lodash: '_'
      },
      name: pkg.name,
      file: pkg.browser,
      format: 'umd'
    },
    {
      file: pkg.main,
      format: 'cjs'
    },
    {
      file: pkg.module,
      format: 'es'
    }
  ]
};

Rollup support multiple outputs with the same input. But sometime we want to apply different plugins for these outputs. The most common scenario is apply the terser plugin for a minify bundle. Before we can write a config array, but there are a lot of duplicate code and operations.

This plugin (maybe not a plugin) gives you a slightly elegant and efficient solution for this scene.

import plugins, {when, whenAll, prop, format, file} from 'rollup-plugin-by-output';

{
  //...
  plugins: [pluginA, when(filter, pluginB), pluginsC, ..., ...whenAll(anotherFilter, pluginD, pluginE)]
}

same as:

{
  // ...
  plugins: plugins(pluginA,
    [filter, pluginB],// same as when
    pluginsC, ..., 
    [anotherFilter, pluginD, pluginE] // same as whenAll and flat
  )
}

The filter is a predicate function, the parameter is an output config object. If the filter return a truthy value, the rest plugins will be apply for the output.

when and whenAll is convenient for few filters and plugins is convenient for multiple filters.

There are three simple but useful filter helpers: prop, format, file.

With them you can write like:

// output 
[
  {
    name: pkg.name,
    file: pkg.browser,
    format: 'umd'
    }
]
when(format('umd'), pluginA)
// same as
when(format(/^umd$/), pluginA)
// same as
when(format(f => f === 'umd'), pluginA)
when(file(pkg.browser), pluginA)
format = filter => prop('format', filter)
file = filter => prop('file', filter)

• lib-starter

# develop
npm start
# build
npm run build
# test
npm test
# commit changes
npm run commit
# publish
npm publish

MIT