Babel 6 regeneratorRuntime is not defined

babel-polyfill (deprecated as of Babel 7.4) is required. You must also install it in order to get async/await working.

npm i -D babel-core babel-polyfill babel-preset-es2015 babel-preset-stage-0 babel-loader

package.json

"devDependencies": {  "babel-core": "^6.0.20",  "babel-polyfill": "^6.0.16",  "babel-preset-es2015": "^6.0.15",  "babel-preset-stage-0": "^6.0.15"}

.babelrc

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

.js with async/await (sample code)

"use strict";export default async function foo() {  var s = await bar();  console.log(s);}function bar() {  return "bar";}

In the startup file

require("babel-core/register");require("babel-polyfill");

If you are using webpack you need to put it as the first value of your entry array in your webpack configuration file (usually webpack.config.js), as per @Cemen comment:

module.exports = {  entry: ['babel-polyfill', './test.js'],  output: {    filename: 'bundle.js'         },  module: {    loaders: [      { test: /\.jsx?$/, loader: 'babel', }    ]  }};

If you want to run tests with babel then use:

mocha --compilers js:babel-core/register --require babel-polyfill

NoteIf you're using babel 7, the package has been renamed to @babel/plugin-transform-runtime.

Besides polyfill, I use babel-plugin-transform-runtime. The plugin is described as:

Externalize references to helpers and builtins, automatically polyfilling your code without polluting globals. What does this actually mean though? Basically, you can use built-ins such as Promise, Set, Symbol etc as well use all the Babel features that require a polyfill seamlessly, without global pollution, making it extremely suitable for libraries.

It also includes support for async/await along with other built-ins of ES 6.

$ npm install --save-dev babel-plugin-transform-runtime

In .babelrc, add the runtime plugin

{  "plugins": [    ["transform-runtime", {      "regenerator": true    }]  ]}

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"]    ]}