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README.md
babel-plugin-transform-es2015-modules-commonjs
This plugin transforms ES2015 modules to CommonJS.
Babel 6 Changes
Babel 6 changed some behavior by not doing
module.exports = exports['default']
anymore in the modules transforms.There are some caveats, but you can use babel-plugin-add-module-exports, so that updating to Babel 6 isn't a breaking change since users that don't use ES modules don't have to do
require("your-module").default
.However, it may not match how Node eventually implements ES modules natively given the the current proposal.
Example
In
export default 42;
Out
Object.defineProperty(exports, "__esModule", {
value: true
});
exports.default = 42;
Installation
npm install --save-dev babel-plugin-transform-es2015-modules-commonjs
Usage
Via .babelrc
(Recommended)
.babelrc
// without options
{
"plugins": ["transform-es2015-modules-commonjs"]
}
// with options
{
"plugins": [
["transform-es2015-modules-commonjs", {
"allowTopLevelThis": true
}]
]
}
Via CLI
babel --plugins transform-es2015-modules-commonjs script.js
Via Node API
require("babel-core").transform("code", {
plugins: ["transform-es2015-modules-commonjs"]
});
Options
loose
boolean
, defaults to false
.
As per the spec, import
and export
are only allowed to be used at the top
level. When in loose mode these are allowed to be used anywhere.
And by default, when using exports with babel a non-enumerable __esModule
property
is exported.
var foo = exports.foo = 5;
Object.defineProperty(exports, "__esModule", {
value: true
});
In environments that don't support this you can enable loose mode on babel-plugin-transform-es2015-modules-commonjs
and instead of using Object.defineProperty
an assignment will be used instead.
var foo = exports.foo = 5;
exports.__esModule = true;
strict
boolean
, defaults to false
By default, when using exports with babel a non-enumerable __esModule
property
is exported. In some cases this property is used to determine if the import is the
default export or if it contains the default export.
var foo = exports.foo = 5;
Object.defineProperty(exports, "__esModule", {
value: true
});
In order to prevent the __esModule
property from being exported, you can set
the strict
option to true
.
noInterop
boolean
, defaults to false
By default, when using exports with babel a non-enumerable __esModule
property
is exported. This property is then used to determine if the import is the default
export or if it contains the default export.
"use strict";
var _foo = require("foo");
var _foo2 = _interopRequireDefault(_foo);
function _interopRequireDefault(obj) {
return obj && obj.__esModule ? obj : { default: obj };
}
In cases where the auto-unwrapping of default
is not needed, you can set the
noInterop
option to true
to avoid the usage of the interopRequireDefault
helper (shown in inline form above).