regenerator-runtime/runtime after regenerator-runtime does not work

[julien-f]

require('regenerator-runtime/runtime') does not work if regenerator-runtime has been previously required.

require('regenerator-runtime')

// regeneratorRuntime is undefined
console.log(global.regeneratorRuntime)

require('regenerator-runtime/runtime')

// regeneratorRuntime is still undefined
console.log(global.regeneratorRuntime)

Repro repo.

[julien-f]

I think we should clear the require cache at the end of runtime-module.js:

delete require.cache[require('./path').path]

[benjamn]

Why not just define it globally (or better, just locally) yourself?

Doing anything with require.cache would make this code Node-specific, so that's not really an option.

[julien-f]

babel-runtime@6 use regenerator-runtime but @babel/preset-env@7 with the polyfill option is using regenerator-runtime/runtime.

So when I use a dependency using @babel/preset-env in my babel-runtime application, it fails with regeneratorRuntime is not defined.

[jquense]

lost a few hours trying to figure out why the runtime was inexplicably disappearing in a webpack app. this seems like really weird behavio (i'm sure there is a reason). Why not have the module version not add a global and have a polyfill import that requires it and appends to the global object which is a lot more common of a pattern for these sorts of things..

[benjamn]

Please note that #353 has landed as of regenerator-runtime@0.13.0. While this version is not yet used by @babel/runtime, the conversion to CommonJS is very likely to affect this issue (hopefully in positive ways!), so I would encourage you to review those changes if you have a minute.

[wmertens]

Aha! I'm using pnpm which uses a non-flat modules layout and the reason I'm getting a failing build is because I added regenerator-runtime with the wrong version to the top of the modules tree :-(