Commonjs - preserveModules support

[Kabe0]

• Rollup Plugin Name: commonjs
• Rollup Plugin Version: latest

Feature Use Case

When preserveModules on output is set to true, the commonjs plugin currently creates invalid files in the _virtual folder. Example of this is something as simple as a import like

import VueFroala from "vue-froala-wysiwyg/dist/vue-froala.js";

When I attach a debugger to the plugin process, the transform is showing

~/Documents/Experiments/Rollup/node_modules/vue-froala-wysiwyg/dist/vue-froala.js?commonjs-module

Ext: .js?commonjs-module

That makes a file in the _virtual folder called
vue-froala.js_commonjs-module
which is not readable in the browser...

Feature Proposal

Change the way new ID's are generated inside the application. Currently in the helper.js, it has multiple SUFFIX's defined. If they were to have a .js extension added to the end, the files would function as expected. While the hack below works alright, it will create weird files with two .js extensions which is not ideal.

export const PROXY_SUFFIX = '?commonjs-proxy.js';
export const REQUIRE_SUFFIX = '?commonjs-require.js';
export const EXTERNAL_SUFFIX = '?commonjs-external.js';
export const EXPORTS_SUFFIX = '?commonjs-exports.js';
export const MODULE_SUFFIX = '?commonjs-module.js';

[lukastaegert]

By "invalid" you just mean that there is no extension? Browsers should have no problem reading JavaScript files without extensions as they do not look at extensions at all, they just look at MIME types. It could however be that your server has a problem inferring the correct MIME type if there is no extension.

[Kabe0]

Yes that's what I meant.

If someone however is using the browser without a server running it won't work. Even with a MIME type specified, having no extension can result in some pretty weird behaviour. I have seen browsers (such as Chrome) cache a home page in place of a vendor resource, and not release it even with a cache reset. In general it's not a great idea to infer the extension of a file.

[BPScott]

I think this and #1031 share an underlying issue.

I think the general solution to both these issues is rollup/rollup#4269 - making it so virtual files pick up their filename based upon output.entryFileNames - which by default will give files created from virtual chunks a .js extension on disk, rather than not performing any filename transform at all.

There have been various other bandaid fixes relating to this issue too rollup/rollup-plugin-commonjs#373 / rollup/rollup-plugin-babel#296