使用webpack解析异步功能的问题

Question

I'm trying to get webpack to parse a javascript file that is using the new async/await syntax, but it keeps giving me a parsing error.

Here is my webpack.config.js file:

module.exports = {
  entry: {
    foo: './foo.js'
  },
  output: {
    filename: 'webpack-compiled.js'
  },
  module: {
    loaders: [
      {
        test: /\.js$/,
        loader: 'babel-loader',
        exclude: /node_modules/
      }
    ]
  }
}

My package.json file:

{
  "name": "async-func-test",
  "version": "1.0.0",
  "description": "",
  "main": "foo.js",
  "scripts": {
    "buildWithBabel": "babel foo.js --out-file babel-compiled.js",
    "buildWithWebpack": "webpack --progress --colors"
  },
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "babel-cli": "^6.18.0",
    "babel-core": "^6.18.2",
    "babel-loader": "^6.2.8",
    "babel-plugin-syntax-async-functions": "^6.13.0",
    "webpack": "^1.13.3"
  }
}

My babel.rc file:

{
  "plugins": [
    "syntax-async-functions"
  ]
}

And the foo.js file:

async function asyncFunc() {
  return 123
}

asyncFunc().then(x => console.log(x))

If I run the npm script 'buildWithBabel', it runs fine with no errors and creates the babel-compiled.js with the proper output.

However if I run the npm script 'buildWithWebpack', I get the following error message:

 ERROR in ./foo.js Module parse failed: C:\\Users\\Redark\\Desktop\\asyncFuncTest\\node_modules\\babel-loader\\lib\\index.js!C:\\Users\\Redark\\Desktop\\asyncFuncTest\\foo.js Unexpected token (1:6) You may need an appropriate loader to handle this file type. SyntaxError: Unexpected token (1:6) 

I don't need to transform the async functions, just parse it. I'm not sure why it's not working for webpack as it should using the "syntax-async-functions" plugin in the .babelrc right?

Answer 1

You will need to use the transform-regenerator plugin as well, syntax-async-functions only allows Babel to parse the input (and then leave it alone). Webpack doesn't understand ES8 syntax yet, that's why it fails without having them transpiled.