swc-plugin-cjs-to-esm

This plugin is under development, not recommended for extensive use.

This is a swc plugin that transforms common CJS patterns to ESM with named exports.

Does not support typescript.

This plugin is more useful for transitioning a larger codebase from cjs to esm over time. It is not recommended as a compiler plugin but rather should be used as a one-time transformation that writes the output to disk and then followed up by a linter.

Usage

npm install <this-package>

Add the plugin to your .swcrc or the config object

Testing

TDD makes life easier here. Most of the tests exist as fixtures in the tests/fixtures directory.

just test

You can optionally pass in the name of the folder the test is in to only run that test.

just test require_ident

Note that this is a substring match and it will match require_ident and require_ident_complex. If you want to match a folder name exactly then add __ at the end. ie require_ident__.

The canonical name for the tests are _exec_tests__fixtures__<folder>__input_js.

Development

This package mostly deals with transforming require and module.exports/exports to import and export respectively. Each unique pattern has its own Visitor implementation and method of handling. These visorts are run in a particular order using the chain!() macro.

It is advisable to first add or modify testing fixtures to represent the feature being supported and then create or modify a visitor to handle the pattern.

Some common utilities are provided such as remove_empty!() which adds some visit_mut_* functions that can remove invalid or empty statements.