“unexpected token import” in Nodejs5 and babel?

Question

In js file, i used import to instead of require

import co from 'co';

And tried to run it directly by nodejs since it said import is 'shipping features' and support without any runtime flag (https://nodejs.org/en/docs/es6/), but i got an error

import co from 'co';
^^^^^^

SyntaxError: Unexpected token import

Then i tried to use babel

npm install -g babel-core
npm install -g babel-cli
npm install babel-core //install to babel locally, is it necessary?

and run by

babel-node js.js

still got same error, unexpected token import?

How could I get rid of it?

Answer 1

1. Install packages: babel-core, babel-polyfill, babel-preset-es2015
2. Create .babelrc with contents: { "presets": ["es2015"] }
3. Do not put import statement in your main entry file, use another file eg: app.js and your main entry file should required babel-core/register and babel-polyfill to make babel works separately at the first place before anything else. Then you can require app.js where import statement.

Example:

index.js

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

app.js

import co from 'co';

It should works with node index.js.

Answer 2

I have done the following to overcome the problem (ex.js script)

problem

$ cat ex.js
import { Stack } from 'es-collections';
console.log("Successfully Imported");

$ node ex.js
/Users/nsaboo/ex.js:1
(function (exports, require, module, __filename, __dirname) { import { Stack } from 'es-collections';
                                                              ^^^^^^

SyntaxError: Unexpected token import
    at createScript (vm.js:80:10)
    at Object.runInThisContext (vm.js:152:10)
    at Module._compile (module.js:624:28)
    at Object.Module._extensions..js (module.js:671:10)
    at Module.load (module.js:573:32)
    at tryModuleLoad (module.js:513:12)
    at Function.Module._load (module.js:505:3)
    at Function.Module.runMain (module.js:701:10)
    at startup (bootstrap_node.js:194:16)
    at bootstrap_node.js:618:3

solution

# npm package installation
npm install --save-dev babel-preset-env babel-cli es-collections

# .babelrc setup
$ cat .babelrc
{
  "presets": [
    ["env", {
      "targets": {
        "node": "current"
      }
    }]
  ]
}

# execution with node
$ npx babel ex.js --out-file ex-new.js
$ node ex-new.js
Successfully Imported

# or execution with babel-node
$ babel-node ex.js
Successfully Imported

Answer 3

It may be that you're running uncompiled files. Let's start clean!

In your work directory create:

• Two folders. One for precompiled es2015 code. The other for babel's output. We'll name them "src" and "lib" respectively.

• A package.json file with the following object:

  { 
    "scripts": {
        "transpile-es2015": "babel src -d lib"
    },
    "devDependencies": {
        "babel-cli": "^6.18.0",
        "babel-preset-latest": "^6.16.0"
    }
  }
  

• A file named ".babelrc" with the following instructions: {"presets": ["latest"]}

• Lastly, write test code in your src/index.js file. In your case: import co from 'co'.

Through your console:

• Install your packages: npm install
• Transpile your source directory to your output directory with the -d (aka --out-dir) flag as, already, specified in our package.json: npm run transpile-es2015
• Run your code from the output directory! node lib/index.js

Answer 4

• install --> "npm i --save-dev babel-cli babel-preset-es2015 babel-preset-stage-0"

next in package.json file add in scripts "start": "babel-node server.js"

    {
  "name": "node",
  "version": "1.0.0",
  "description": "",
  "main": "server.js",
  "dependencies": {
    "body-parser": "^1.18.2",
    "express": "^4.16.2",
    "lodash": "^4.17.4",
    "mongoose": "^5.0.1"
  },
  "devDependencies": {
    "babel-cli": "^6.26.0",
    "babel-preset-es2015": "^6.24.1",
    "babel-preset-stage-0": "^6.24.1"
  },
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "start": "babel-node server.js"
  },
  "keywords": [],
  "author": "",
  "license": "ISC"
}

and create file for babel , in root ".babelrc"

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

and run npm start in terminal

Answer 5

From the babel 6 Release notes:

Since Babel is focusing on being a platform for JavaScript tooling and not an ES2015 transpiler, we’ve decided to make all of the plugins opt-in. This means when you install Babel it will no longer transpile your ES2015 code by default.

In my setup I installed the es2015 preset

npm install --save-dev babel-preset-es2015

or with yarn

yarn add babel-preset-es2015 --dev

and enabled the preset in my .babelrc

{
  "presets": ["es2015"]
}

Answer 6

if you use the preset for react-native it accepts the import

npm i babel-preset-react-native --save-dev

and put it inside your .babelrc file

{
  "presets": ["react-native"]
}

in your project root directory

https://www.npmjs.com/package/babel-preset-react-native