9 releases (5 breaking)
0.99.0 | Jul 18, 2024 |
---|---|
0.90.24 | Mar 22, 2024 |
0.90.6 | Feb 23, 2024 |
0.89.2 | Jan 26, 2024 |
0.79.19 | Aug 12, 2023 |
#280 in Testing
24 downloads per month
43KB
736 lines
[SWC plugin] mutable CJS exports
This is a SWC plugin to emit mutable CJS exports.
This SWC plugin has only been tested for compatibility with jest. It should be used with @swc/jest
.
This project was previously called jest_workaround
plugin version
https://swc.rs/docs/plugin/selecting-swc-core
usage
install
npm i -D jest @swc/core @swc/jest swc_mut_cjs_exports
// jest.config.js
const fs = require("node:fs");
const swcrc = JSON.parse(fs.readFileSync(".swcrc", "utf8"));
// If you have other plugins, change this line.
((swcrc.jsc ??= {}).experimental ??= {}).plugins = [
["swc_mut_cjs_exports", {}],
];
module.exports = {
transform: {
"^.+\\.(t|j)sx?$": ["@swc/jest", swcrc],
},
};
Make sure that module.type
is commonjs
in your .swcrc
since this plugin
does not touch non-workaround parts, such as import statements.
FAQ
1. When do I need this?
If you're using the swc compiler to transform your code to comply with the ESM
specification, but you're also using Jest to test it in a CJS environment, you
may encounter issues due to the immutable issue of exports
.
This plugin can help by transforming the export
statements into mutable
exports
.
2. Do I have a better choice?
You may have other options depending on your specific needs:
-
If you're able to run Jest in an ESM environment, you can use swc to transpile TypeScript/JSX syntax or downgrade JavaScript syntax without module conversion. Simply set the value of
module.type
toes6
to achieve this. -
It's possible that some issues related to running Jest in an ESM environment will be resolved over time. Keep an eye on facebook/jest#9430 for updates.
-
If you don't need the behavior of ESM specifically, you can stick with the CJS syntax to get the CJS behavior of
exports
.
These options may be worth considering before using this plugin.
CJS syntax
exports.foo = function foo() {
return 42;
};
CTS(CJS in TypeScript) syntax
export = {
foo: function foo() {
return 42;
},
};
Notes:
- ESM style export means immutable exports when transformed into CJS
- ESM style import means hoisted require when transformed into CJS
3. After upgrading the plugin version, the changes have not taken effect.
This is a known issue. You could remove the Jest cache by running
jest --clearCache
as a workaround.
Dependencies
~9MB
~163K SLoC