Optionally require `es6-promise` and `isomorphic-fetch`

[moretti]

It would be nice if we could optionally avoid to polyfill Promise and window.fetch.
The latest versions of Firefox, Chrome and Opera natively support Promises and window.fetch, so it seems unnecessary. I recently started loading polyfills on demand with webpack in order to reduce the size of the main bundle.

I'm proposing the following structure

• marty.js (or maybe marty-without-polyfills.js): equivalent to the current file, but without polyfills
• polyfills.js: a file containing all polyfills
• index.js (or maybe marty-with-polyfills.js): the entry point of the project with the old behavior

In this way it would be possible not to load polyfills by creating an alias.
With webpack:

module.exports = {
  // ...
  resolve: {
    alias: {
      'marty': 'marty/marty-without-polyfills.js'
    }
  }
};

With browserify:

browserify --require marty:marty/marty-without-polyfills.js

[taion]

Do you have any examples of projects that are structured this way that we can look at?

[moretti]

I created the following example:

https://github.com/moretti/webpack-polyfills-on-demand

If you clone it and run npm start you will notice that polyfills for fetch and Promise are loaded on demand.
For example, Safari 8 will request 2.bundle.js because it doesn't have a native window.fetch implementation.