How to run koa with nodejs v6.11.2

[vaxilicaihouxian]

Nodejs version 6.11.2 is LTS.So I need to use this nodejs version to run koa2.I followed tutorial and code is:

require('babel-register');
const Koa = require('koa');
const app = new Koa();

app.use(async ctx => {
    ctx.body = 'Hello World';
});

app.listen(3000);

Package.json:

{
  "name": "koa",
  "version": "1.0.0",
  "description": "",
  "main": "app.js",
  "dependencies": {
    "babel-cli": "^6.24.1",
    "babel-plugin-transform-async-to-module-method": "6.24.1",
    "babel-register": "6.24.1",
    "koa": "2.3.0"
  },
  "devDependencies": {},
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC"
}

But it didn't say how to run app.js?

I try node app.js and it did not work.
Any helps?

[fl0w]

You need to require the file for babel hook to work.

[vaxilicaihouxian]

How to require the file for babel hook to work ?
I have already require the file babel-register.
I'm newer,sorry about that.

[fl0w]

Take a look at this example. I haven't used babel in a while myself.

Any specific reason to why you're not using node 8? It is recommended.

[vaxilicaihouxian]

I think that LTS version may be a good choice for me because I'm new in nodejs.I wonder why the official tutorial didn't show how to work with node 6.

[fl0w]

@vaxilicaihouxian It does, under "Installation" > "Async Functions with Babel".
node 8 will be under LTS in October, I would personally recommend you to start using node 8 instead. This way you can omit babel (which can be a bit cumbersome for beginners) and focus on creating awesome stuff instead!

[vaxilicaihouxian]

This is my code (follow the "Async Functions with Babel").

//index.js
require("babel-core/register");
const app = require('./app.js');

//app.js
const Koa = require('koa');
const app = new Koa();
app.use(async ctx => {
  ctx.body = 'Hello World';
});

app.listen(3000);

I run node index.js and it shows:

ubuntu@ubuntu-xenial:/codes/koa$ node index.js
/codes/koa/node_modules/babel-core/lib/transformation/file/index.js:590
      throw err;
      ^

TypeError: /codes/koa/app.js: Property value expected type of string but got null
    at Object.validate (/codes/koa/node_modules/babel-types/lib/definitions/index.js:161:13)
    at validate (/codes/koa/node_modules/babel-types/lib/index.js:505:9)
    at Object.builder (/codes/koa/node_modules/babel-types/lib/index.js:466:7)
    at File.addImport (/codes/koa/node_modules/babel-core/lib/transformation/file/index.js:353:54)
    at PluginPass.addImport (/codes/koa/node_modules/babel-core/lib/transformation/plugin-pass.js:52:43)
    at PluginPass.Function (/codes/koa/node_modules/babel-plugin-transform-async-to-module-method/lib/index.js:14:28)
    at newFn (/codes/koa/node_modules/babel-traverse/lib/visitors.js:276:21)
    at NodePath._call (/codes/koa/node_modules/babel-traverse/lib/path/context.js:76:18)
    at NodePath.call (/codes/koa/node_modules/babel-traverse/lib/path/context.js:48:17)
    at NodePath.visit (/codes/koa/node_modules/babel-traverse/lib/path/context.js:105:12)

If I can not fix that I will change to use node version 8.

[fl0w]

This works for me.

index.js

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

app.js

'use strict'

const Koa = require('koa')
const app = new Koa()

app.use(async ctx => {
  ctx.body = 'Hello World'
})

app.listen(3000)

.babelrc

{
  "presets": [
    "node6"
  ],
  "plugins": [
    ["transform-async-to-module-method", {
        "module": "bluebird",
        "method": "coroutine"
    }]
  ]
}

package.json

{
  ...
  "dependencies": {
    "babel-plugin-transform-async-to-module-method": "^6.24.1",
    "babel-polyfill": "^6.23.0",
    "babel-preset-node6": "^11.0.0",
    "babel-register": "^6.24.1",
    "bluebird": "^3.5.0"
  }
}

[albertogasparin]

The problem is that you have to include babel in a different file before stating using ES2015+ code.
So you have to create a "loader" file and require your code from it:

// loader.js
require("babel-core/register");
// No ES2015+ code here!
require("./index.js");

However, that might not be enough as babel does not parse node_modules by default. So you might need to add the ignore option in order to successfully load Koa (and that will make babel compilation much slower). So, I second what @fl0w already said: Node 8 is stable and will be LTS in a couple of months. By using it right now you can avoid over-complicating your project and moving to a different node version half-way 😉.

[vaxilicaihouxian]

OK.I will try it( don't know how the official setting work,but whatever).
And I think I should use node 8 right now.
Thanks!!
Maybe the we don't need babel in the future.

[slaskis]

I really liked to use async-to-gen and skip babel entirely (there's an example in a comment in another issue)

[fl0w]

Or use node 8 and skip babel entirely :)

[jonyrock]

You can compile project with webpack to server.js and then compile it again with preset with target to node 6.11.2

Sorry, I don't have time to make a simple clear solution, but you can try do digg code: https://github.com/hastic/hastic-server/blob/9000adefcc79e48e45089f9d25960f7805a37e48/server/package.json

Also I can't say that it is the BEST solution, but it works.