Babel 6 regeneratorRuntime is not defined

Question

I\'m trying to use async, await from scratch on Babel 6, but I\'m getting regeneratorRuntime is not defined.

.babelrc file

{
    \"presets\": [ \"es2         


        

Answer 1

If you are building an app, you just need the @babel/preset-env and @babel/polyfill:

npm i -D @babel/preset-env
npm i @babel/polyfill

(Note: you don't need to install the core-js and regenerator-runtime packages because they both will have been installed by the @babel/polyfill)

Then in .babelrc:

{
  "presets": [
    [
      "@babel/preset-env",
      {
        "useBuiltIns": "entry"  // this is the key. use 'usage' for further codesize reduction, but it's still 'experimental'
      }
    ]
  ]
}

Now set your target environments. Here, we do it in the .browserslistrc file:

# Browsers that we support

>0.2%
not dead
not ie <= 11
not op_mini all

Finally, if you went with useBuiltIns: "entry", put import @babel/polyfill at the top of your entry file. Otherwise, you are done.

Using this method will selectively import those polyfills and the 'regenerator-runtime' file(fixing your regeneratorRuntime is not defined issue here) ONLY if they are needed by any of your target environments/browsers.