Simple Example for Dynamic Imports

[Patrick Kuhlmann]

Hey

I'm writing a simple application with rollup and vanilla js utilizing dynamic imports. As last step I try to use closure compiler but this is harder than I imagined.

I tried several flags maybe in wrong combination: 

language_in ECMASCRIPT_NEXT

js_module_root

env BROWSER

module

dependency_mode LOOSE

module_resolution

If there is not support yet would I be able to tell closure compiler to ignore imports and let him do the optimization for everything it understands?

Sincerly

Patrick

[Yiting Wang]

Hi Patrick,

To confirm, are you using the Rollup plugin for Closure Compiler? https://github.com/ampproject/rollup-plugin-closure-compiler

I have not used Rollup before, but it seems from the documentation that you could pass in the compiler flags by specifying them as key-value pairs in your rollup.config.js

For example,

// rollup.config.js
import compiler from '@ampproject/rollup-plugin-closure-compiler';

export default {
  input: 'main.js',
  output: {
    file: 'bundle.js',
    format: 'iife',
  },
  plugins: [
    compiler({
      language_in: 'ECMASCRIPT_NEXT',
      js_module_root: 'some/path/prefix'
    }),
  ],
}

Have you tried the above? What is not working for you?

Best,

Yiting

[Patrick Kuhlmann]

I tried it but it looks like it swallows the error message so I just used the cli thats provided by https://github.com/google/closure-compiler

So I got an error too but I cannot say it is the same but I assume it

[Yiting Wang]

What error message are you getting when using the command line?

[Patrick Kuhlmann]

google-closure-compiler --js=index.js --js_output_file=out.js --language_in=ECMASCRIPT_NEXT --js_module_root './'

index.js:690: ERROR - Parse error. primary expression expected

      await import('./chunk-c64f0c6a.js');

                  ^

1 error(s), 0 warning(s)

[Yiting Wang]

Hi Patrick,

The compiler currently does not support dynamic imports, hence the parse error. Here's the tracking issue for this in GitHub. https://github.com/google/closure-compiler/issues/2770 

In the meantime, you can try getting around this by using the standard kind of import. 

Best,

Yiting

[Patrick Kuhlmann]

Thanks for the input would there be any way to let the compiler ignore specific lines like the imports?

[Yiting Wang]

AFAIK that is not possible, unfortunately.

[Patrick Kuhlmann]

I see thanks for the help!