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Babel Register with Node and Async - 16 Dec 2015


If you’re looking to use babel with koa, then here’s a quick guide to get you started.

The first thing you’ll need to do is install babel-register.

  npm install babel-register --save

You’ll then want to setup a new entry file for your application. Here’s an example of using index.js to load babel-register and app.js.

  require('babel-register')
  require('./app.js')

You’re now setup to use Babel features in your application. If you’re using Koa though, then you likely want access to async functions, which requires a little more setup.

The first thing you’ll need to do is install the async plugin:

  npm install babel-plugin-transform-async-to-generator --save

Once that’s done, you’ll need to setup a .babelrc file:

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

You can now take advantage of async functions in your application. Here’s an example of a logger that uses async.

  module.exports = (app) => {
    app.use(async (ctx, next) => {
      const start = new Date
      await next()
      const ms = new Date - start
      console.log(`${ctx.method} ${ctx.url} - ${ms} ms`)
    })

    return app
  }