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": [ "es2015", "stage-0" ]
}

package.json file

"devDependencies": {
    "babel-core": "^6.0.20",
    "babel-preset-es2015": "^6.0.15",
    "babel-preset-stage-0": "^6.0.15"
}

.js file

"use strict";
async function foo() {
  await bar();
}
function bar() { }
exports.default = foo;

Using it normally without the async/await works just fine. Any ideas what I'm doing wrong?

Answer 1

1 - Install babel-plugin-transform-async-to-module-method, babel-polyfil, bluebird , babel-preset-es2015, babel-core :

npm install babel-plugin-transform-async-to-module-method babel-polyfill bluebird babel-preset-es2015 babel-core

2 - Add in your js babel polyfill:

import 'babel-polyfill';

3 - Add plugin in your .babelrc:

{
    "presets": ["es2015"],
    "plugins": [
      ["transform-async-to-module-method", {
        "module": "bluebird",
        "method": "coroutine"
      }]
    ]
}

Source : http://babeljs.io/docs/plugins/transform-async-to-module-method/

Answer 2

The targeted browsers I need to support already support async/await, but when writing mocha tests, without the proper setting I still got this error.

Most of the articles I googled are outdated, including the accepted answer and high voted answers here, i.e. you don't need polyfill, babel-regenerator-runtime, babel-plugin-transform-runtime. etc. if your target browser(s) already supports async/await (of course if not you need polyfill)

I don't want to use webpack either.

Tyler Long's answer is actually on the right track since he suggested babel-preset-env (but I omitted it first as he mentioned polifill at the beginning). I still got the ReferenceError: regeneratorRuntime is not defined at the first then I realized it was because I didn't set the target. After setting the target for node I fix the regeneratorRuntime error：

  "scripts": {
    //"test": "mocha --compilers js:babel-core/register"
    //https://github.com/mochajs/mocha/wiki/compilers-deprecation
    "test": "mocha --require babel-core/register"
  },
  "devDependencies": {
    "babel-core": "^6.26.3",
    "babel-preset-env": "^1.7.0",
    "mocha": "^5.2.0"
  },
  //better to set it .bablerc, I list it here for brevity and it works too.
  "babel": {
    "presets": [
      ["env",{
        "targets": {
          "node": "current"
           "chrome": 66,
           "firefox": 60,
        },
        "debug":true
      }]
    ]
  }

Answer 3

Babel 7 Users

I had some trouble getting around this since most information was for prior babel versions. For Babel 7, install these two dependencies:

npm install --save @babel/runtime 
npm install --save-dev @babel/plugin-transform-runtime

And, in .babelrc, add:

{
    "presets": ["@babel/preset-env"],
    "plugins": [
        ["@babel/transform-runtime"]
    ]
}

Answer 4

To babel7 users and ParcelJS >= 1.10.0 users

npm i @babel/runtime-corejs2
npm i --save-dev @babel/plugin-transform-runtime @babel/core

.babelrc

{
  "plugins": [
    ["@babel/plugin-transform-runtime", {
      "corejs": 2
    }]
  ]
}

taken from https://github.com/parcel-bundler/parcel/issues/1762

Answer 5

I had this problem in Chrome. Similar to RienNeVaPlu͢s’s answer, this solved it for me:

npm install --save-dev regenerator-runtime

Then in my code:

import 'regenerator-runtime/runtime';

Happy to avoid the extra 200 kB from babel-polyfill.

Answer 6

I have async await working with webpack/babel build:

"devDependencies": {
    "babel-preset-stage-3": "^6.11.0"
}

.babelrc:

"presets": ["es2015", "stage-3"]