A Babel 7 plugin transform to convert CommonJS into ES Modules
A Babel 7 compatible transform to convert Node-style CommonJS modules into the ES module specification. This was created specifically for an experimental module bundler, but has many uses outside of that initial use case. All major browsers have shipped support for ESM and Node currently has experimental support behind a flag. Babel offers a bridge to bring the old to the new, which is humorous given the origins of Babel which brought the new to the old. This module can reconcile differences as best as possible without resorting to hacks.
The goal of this transform is to produce spec-compliant code. Any behavior that diverges will throw by default. There are escape hatches however, if you know what they do.
This module will ignore existing ESM modules by default, so long as they do not
reference the following globals: require
, module.exports
, or exports
.
What to expect:
module.exports
intact, no tricks to separate this objectWhat not to expect:
require.extensions
support, as this is a runtime concernNotable features not supported:
exports["I'mateapot"]
) will only be available on the default exportNotable features supported:
this
npm install --save-dev babel-plugin-transform-commonjs
Update your babel configuration:
{
"plugins": ["transform-commonjs"]
}
Now code like this:
var { readFileSync } = require('path');
exports.readFileSync = readFileSync;
Will turn into this:
import { readFileSync as _readFileSync } from "path";
var module = {
exports: {}
};
exports.readFileSync = _readFileSync;
export const readFileSync = _readFileSync;
export default module.exports;
synchronousImport
- Convert non-static require to a compatible dynamic
import. If the bundler can inline and link synchronously, this should be
okay, although this will produce invalid code for any other case. Use with
caution!
{
"plugins": [
["transform-commonjs", { "synchronousImport": true }]
]
}
exportsOnly
- Keep require
calls and process exports only.
{
"plugins": [
["transform-commonjs", { "exportsOnly": true }]
]
}