Optimisation

[Rich-Harris]

This PR allows the majority of CommonJS modules to be transformed without wrapping. In other words, this...

// foo.js
module.exports = 42;

...becomes this...

var foo = 42;

export default foo;
export { foo as __moduleDefault };

...rather than this:

var foo = createCommonjsModule(function(module) {
  module.exports = 42;
});

export default foo;
export { foo as __moduleDefault };

In many cases this makes modules tree-shakeable. It doesn't yet optimise situations like this:

module.exports = {
  foo: foo,
  bar: bar
};

Will release as 5.0.0 (major version bump) as it depends on Rollup 0.35.

[montogeek]

Will this work with Lodash?

[Rich-Harris]

I'd recommend using lodash-es rather than lodash. This won't have any effect on the tree-shakeability of the library itself – all it means is that in a situation like this...

exports.a = 1;
exports.b = 2;

...where a is used in the bundle but b is not, the b can be removed. Previously there was no way to remove any code from a transformed CommonJS module.

[montogeek]

Thanks!

[jdalton]

@montogeek until things improve on the tree-shaking front of rollup and webpack 2 you'll still want to use babel-plugin-lodash for lodash or lodash-es.

[montogeek]

Thanks @jdalton It should be compatible with https://github.com/rollup/rollup-plugin-babel, right?