Producing CommonJS modules

[wiktortomczak]

Is it possible to use Closure compiler to produce a standalone CommonJS module, for use by dependent external (not managed by the compiler) JS code? That is, to produce a single file that exports its public symbols via CommonJS special exports variable?

The problem I'm running into is that:

• with --process_common_js_modules, the compiler renames exports to module$path$to$source, making it impossible to import the compiled source as a CommonJS module
• without --process_common_js_modules, the compiler does not resolve CommonJS require imports, so other CommonJS modules can't be used as the target module's building blocks.

I believe I understand the motivation for renaming exports (prevent name clashes between multiple CommonJS modules concatenated in the single compiled file), but this is not enough if the compiled file is meant to be imported by some other code. Ideally, the exports variable would not be renamed in the top-level module that defines the module's public symbols (it still needs to be renamed, as is already the case, in implementation modules the top-level module imports itself).

[ChadKillingsworth]

Not currently. You can pull some tricks with the output_wrapper flag, but that's about it.

The primary use is module bundling and Closure Compiler is the envy of most tools because of how effective it is.

This issue isn't restricted to CommonJS modules. ES modules are in the same boat.

[wiktortomczak]

Thanks. I'll give output_wrapper a try.

I tried to modify ProcessCommonJSModules.java to skip renaming for entry point modules but it's tricky.

On a related note, is the --module flag relevant, specifically --module=...:auto? It appears to produce the same output as without the flag.

[ChadKillingsworth]

The --module flag probably doesn't do what you think (it's not related to JS Modules at all). It's for code splitting and is based on the order and count of files. The auto portion allows the count to be auto-adjusted for the base module definition. See http://stackoverflow.com/questions/10395810/how-do-i-split-my-javascript-into-modules-using-googles-closure-compiler/10401030#10401030