I am using Parcel to bundle my project and jest to run my tests.

Everything works fine, but on tests that I have the async/await keyword, I had to import regenerator-runtime/runtime

Like this:

import "regenerator-runtime/runtime"

test("read armored key", async() => {

})

And this work.

But without this import (import "regenerator-runtime/runtime") I got this error message:

ReferenceError: regeneratorRuntime is not defined

How can I change my project to run without this import on tests with async?

Example:

I am using Parcel to bundle my project and jest to run my tests.

Everything works fine, but on tests that I have the async/await keyword, I had to import regenerator-runtime/runtime

Like this:

import "regenerator-runtime/runtime"

test("read armored key", async() => {

})

And this work.

But without this import (import "regenerator-runtime/runtime") I got this error message:

ReferenceError: regeneratorRuntime is not defined

How can I change my project to run without this import on tests with async?

Example: https://github.com/skhaz/parcel-regeneratorRuntime-is-not-defined

• javascript
• jestjs
• babeljs
• parceljs

• 1 if you're targeting newer browsers you could set the browserslist params to target newer browsers. like this in a package.json file: "browserslist": [ "Chrome 70", "Edge 17", "Firefox 68", "Opera 60", "Safari 12" ] ..... google to see how to use browserslist without package.json if your project is set up in another way. – Getter Jetter Commented Jan 20, 2021 at 3:22
• It's for NodeJS, not for browsers – Rodrigo Commented Jan 20, 2021 at 11:08

3 Answers 3

Depending its version, not all features available in your browser runtime will work in the Node runtime. Promises (with await/async) are supported in current versions of node, but since you are using Parcel, which by default uses Babel, your async/await calls will be compiled to use regenerator-runtime, a polyfill for that functionality. You can either import "regenerator-runtime/runtime" in every entry file (not recommended if you don't need the polyfill!), or you can tell babel what your runtime is.

You should be able to get it to work with the @babel/preset-env preset, configured like so in your .babelrc:

{
  "presets": [
    [
      "@babel/preset-env",
      {
        "targets": {
          "node": "10" // the target node version, boolean true, or "current".
        }
      }
    ]
  ]
}

See this Medium article for more information about configuring babel for this:

I found this answer to my troubles and it worked when I implemented it.

As I know that you can configure @babel/preset-env to compile against current node version which is described here then it should work:

.babelrc

{
  "presets": [
    [
      "@babel/preset-env",
      {
        "targets": {
          "node": "current"
        }
      }
    ]
  ]
}

When using Webpack, or Parcel, add the below to package.json:

"browserslist": [
  "since 2017-06"
]

or

"browserslist": [
  "last 3 Chrome versions"
]