babel-plugin-async-to-plain-generator

babel-plugin-async-to-plain-generator

While working with KoaJS v1 we found that the resulting output from transform-async-to-generator was incompatible with Koa's requirements - that app.use must be passed a generator function.

This plugin was created by modifying the transform-async-to-generator plugin. While that plugin works well in most situations, it curiously (and extraneously?) wraps async functions and results in a generator function wrapped in a regular function of the same name. This plugin was created so that babel would produce plain old vanilla generator functions from async function declarations.

Transformations:

// in

[].forEach(async (a) => {
  await a;
});

async function foo (bar) {
  await bar;
};

// out

[].forEach(function* (a) {
  yield a;
});

function* foo (bar) {
  yield bar;
}

Installation

$ npm install babel-plugin-async-to-plain-generator

Usage

Via .babelrc (Recommended)

.babelrc

{
  "plugins": ["async-to-plain-generator"]
}

Via CLI

$ babel --plugins async-to-plain-generator script.js

Via Node API

require("babel-core").transform("code", {
  plugins: ["async-to-plain-generator"]
});