@miyaokamarina/rollup-plugin-override

Rollup Plugin Override

Compile-time expression substitution. Similar to @rollup/plugin-replace, but robust and safe.

Usage

yarn add -D @miyaokamarina/rollup-plugin-override

npm install --save-dev @miyaokamarina/rollup-plugin-override

import override from '@miyaokamarina/rollup-plugin-override';

export default {
    plugins: [
        override({
            mappings: {
                'process.env.NODE_ENV': `'production'`,
                'OPT_LEVEL': `3`,
                'BUILD_ID': JSON.stringify(uuid()),
            },
        }),
    ],
};

Options

• include, exclude — filter patterns to limit files the plugin processes.
• ignoreScope (default: false) — force enable replacement processing even in scopes that have bindings, shadowing the expression to be rewritten.
• mappings — a record of key-value mappings; values must be strings containing valid JavaScript expressions.

Why

Unlike the official @rollup/plugin-replace, this plugin is more robust in edge cases:

• Doesn’t care of the exact code formatting:

  assert(process.env.NODE_ENV === 'production');
  assert(process.env['NODE_ENV'] === 'production');
  assert(process['env'][`NODE_ENV`] === 'production');
  
  assert(
      process
      .env
      .NODE_ENV === 'production'
  );

• Doesn’t rewrite binding names, assignment LHS expressions, etc.:

  process.env.NODE_ENV = 'production';
  //          ↑ writing the real env variable
  
  import { BUILD_ID } from '#constants';
  
  const { BUILD_ID } = whatever;
  const f = BUILD_ID => g();
  
  class App {
      BUILD_ID;
      OPT_LEVEL() {}
  }

• Respects the scope:

  const f = BUILD_ID => g(BUILD_ID);
  //                      ↑ “global” `BUILD_ID` is shadowed
  //                        by the function parameter,
  //                        so it will not be rewritten
  
  import process from 'node:process';
  
  console.log(process.env.NODE_ENV);
  //                      ↑ reading the real env variable

Limitations

• No expressions except plain identifiers and member expressions can be rewritten.
• Member expression properties must be either plain identifiers, or string/template literal subscripts.
• Template literals with substitutions are not supported.
• The value of string or template literal must be a valid JavaScript identifier.

Why Babel

Because it has an easy to use all-in-one API.

Support

If you have any issues, feel free to fork this plugin, or contact me on Telegram https://t.me/miyaokamarina

License

MIT © 2023 Yuri Zemskov