Load ES modules in parallel

[michael-lloyd-morris]

🤔 What's the problem you've observed?

Current ES6 code is using await in a loop - a bad pattern.

for (const path of importPaths) {
    await importer(pathToFileURL(path))
  }

This means the es modules load one at a time. There's a better pattern.

✨ Do you have a proposal for making it better?

  const importPromises:Array<Promise<void>> = [];
  importPaths.map((path) => {
    importPromises.push(importer(pathToFileURL(path)))
  });

  await Promise.all(importPromises);

📚 Any additional context?

This is a simple optimization. Going to create a branch for it now and issue a PR.

[davidjgoss]

There’s an implicit contract around the loading of support files in a predictable order which affects the order of hooks, so this would arguably be a breaking change.

[davidjgoss]

(Not saying we shouldn't do it - it just probably needs to be a major release.)

[michael-lloyd-morris]

A cli flag perhaps?

--processESModulesInParallel

Default is false for the current, and the next major will switch it to default to true.

Anyway, there is now a pull request for this here: https://github.com/cucumber/cucumber-js/pull/2263

Let's continue the conversation there - I'll close this.