regeneratorRuntime is not defined when using generator

[domoritz]

{
  "name": "out",
  "source": "index.js",
  "dependencies": {
    "microbundle": "^0.12.3"
  }
}

function *hello() {
    return 42
}

console.log(hello())

running

$ yarn
$ yarn microbundle
$ node node dist/out.js

Results in this error

/Users/dominik/Code/microbundle-async/dist/out.js:1
var r=regeneratorRuntime.mark(e);function e(){return regeneratorRuntime.wrap(function(r){for(;;)switch(r.prev=r.next){case 0:return r.abrupt("return",42);case 1:case"end":return r.stop()}},r)}console.log(e());
      ^

ReferenceError: regeneratorRuntime is not defined
    at Object.<anonymous> (/Users/dominik/Code/microbundle-async/dist/out.js:1:7)
    at Module._compile (internal/modules/cjs/loader.js:1251:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1272:10)
    at Module.load (internal/modules/cjs/loader.js:1100:32)
    at Function.Module._load (internal/modules/cjs/loader.js:962:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:72:12)
    at internal/main/run_main_module.js:17:47

It works if I add import 'regenerator-runtime/runtime'; to the top of the js file but it would be great if I didn't have to guess that this extra import is required (and it won't be required in the modern build for example: node dist/out.modern.js works).

[developit]

This is a bug. I think it should be fixed by #707.

To clarify - are you using microbundle --target node? Or do you have a Babel config (.babelrc, babel.config.js, "babel" package.json field)?

[domoritz]

Thanks for the quick response.

To clarify - are you using microbundle --target node?

I am trying to move https://github.com/vega/vega over to microbundle and mainly target browsers. I ran into the problem above because of https://github.com/vega/vega/blob/a8e6991411c2c5c4805320f87276e9861e80d69c/packages/vega-statistics/src/numbers.js#L1.

Or do you have a Babel config (.babelrc, babel.config.js, "babel" package.json field)?

We do have a babel config in the repo (although I will probably get rid of it once I have switched over to microbundle). I was able to reproduce the issue without any special files (just the code above).

[domoritz]

So yeah, my issue is similar to #704 but I am not targeting node.

[developit]

Alrighty. I need to double-check my fix there for the browser target.

[domoritz]

Sweet. Thanks!

[yovanoc]

@domoritz @developit Same error for me, there is a fix now?

[domoritz]

I created my own rollup config: https://github.com/vega/vega/blob/master/rollup.config.js.

[developit]

Fixed in 0.13. Please re-open if this is not working still.

[jackmoxley]

This is happening for me in 0.13.0

[eatsjobs]

Still have this error :( there's a patch for this behaviour?

[developit]

Hmm - do you have a custom Babel configuration by chance? Microbundle should be generating code that targets Node 12+, which should never use Regenerator since generators are fully supported.

[YousefED]

@developit I'm running into the same issue with the latest version, without having any custom Babel configuration.

Steps to reproduce:

• Check out https://github.com/YousefED/vscode-lib

npm install
npm run update
npm run build

In the output files (dist), you'll notice several references to regeneratorRuntime

[developit]

@YousefED your package.json has a browserslist configuration that is causing regenerator to be referenced. Specifically, the >0.2% clause will include obscure browsers for which caniuse/browserslist data is known to be incorrect, like QQ Browser and UC Browser (both of which have been Chrome/Webview-based for many years, but the compat data is based on 2016 tests).

[YousefED]

@YousefED your package.json has a browserslist configuration that is causing regenerator to be referenced. Specifically, the >0.2% clause will include obscure browsers for which caniuse/browserslist data is known to be incorrect, like QQ Browser and UC Browser (both of which have been Chrome/Webview-based for many years, but the compat data is based on 2016 tests).

Ah thanks, I think that originated from React defaults from a different project. In any case, when I remove that from package.json, I still have the same issue.

[YousefED]

@developit Not sure if you've seen my comment / would you prefer me to open a new issue? Let me know if there's any other way I help diagnose (or some hints to debug the issue myself)