🍣 A Rollup plugin to convert CommonJS modules to ES6, so they can be included in a Rollup bundle
This plugin requires an LTS Node version (v8.0.0+) and Rollup v1.20.0+.
npm install @rollup/plugin-commonjs --save-dev
rollup.config.js configuration file and import the plugin:
;input: 'src/index.js'output:dir: 'output'format: 'cjs'plugins:;
Some modules contain dynamic
require calls, or require modules that contain circular dependencies, which are not handled well by static imports.
Including those modules as
dynamicRequireTargets will simulate a CommonJS (NodeJS-like) environment for them with support for dynamic and circular dependencies.
Note: In extreme cases, this feature may result in some paths being rendered as absolute in the final bundle. The plugin tries to avoid exposing paths from the local machine, but if you are
dynamicRequirePaths with paths that are far away from your project's folder, that may require replacing strings like
A minimatch pattern, or array of patterns, which specifies the files in the build the plugin should ignore. By default non-CommonJS modules are ignored.
A minimatch pattern, or array of patterns, which specifies the files in the build the plugin should operate on. By default CommonJS modules are targeted.
Search for extensions other than .js in the order specified.
If true, uses of
global won't be dealt with by this plugin.
If false, skips source map generation for CommonJS modules.
Instructs the plugin whether or not to enable mixed module transformations. This is useful in scenarios with mixed ES and CommonJS modules. Set to
true if it's known that
require calls should be transformed, or
false if the code contains env detection and the
require should survive a transformation.
Array[...String | (String) => Boolean]
Sometimes you have to leave require statements unconverted. Pass an array containing the IDs or an
id => boolean function. Only use this option if you know what you're doing!
Using with @rollup/plugin-node-resolve
Since most CommonJS packages you are importing are probably dependencies in
node_modules, you may need to use @rollup/plugin-node-resolve:
// rollup.config.js;;input: 'main.js'output:file: 'bundle.js'format: 'iife'name: 'MyModule'plugins:;
Usage with symlinks
Symlinks are common in monorepos and are also created by the
npm link command. Rollup with
@rollup/plugin-node-resolve resolves modules to their real paths by default. So
exclude paths should handle real paths rather than symlinked paths (e.g.
../common/node_modules/** instead of
node_modules/**). You may also use a regular expression for
include that works regardless of base path. Try this:
Whether symlinked module paths are realpathed or preserved depends on Rollup's
preserveSymlinks setting, which is false by default, matching Node.js' default behavior. Setting
preserveSymlinks to true in your Rollup config will cause
export to match based on symlinked paths instead.
ES modules are always parsed in strict mode. That means that certain non-strict constructs (like octal literals) will be treated as syntax errors when Rollup parses modules that use them. Some older CommonJS modules depend on those constructs, and if you depend on them your bundle will blow up. There's basically nothing we can do about that.
Luckily, there is absolutely no good reason not to use strict mode for everything — so the solution to this problem is to lobby the authors of those modules to update them.