babel-loader jsx SyntaxError: Unexpected token [duplicate]

Question

I'm a beginner in React + Webpack.

I found a weird error in my hello world web app.

I'm using babel-loader in webpack to help me convert jsx into js, but it seems like babel can't understand jsx syntax.

Here are my dependencies:

"devDependencies": {
  "babel-core": "^6.0.14",
  "babel-loader": "^6.0.0",
  "webpack": "^1.12.2",
  "webpack-dev-server": "^1.12.1"
},
"dependencies": {
  "react": "^0.14.1"
}

Here is my webpack.config.js

var path = require('path');
module.exports = {
  entry: ['webpack/hot/dev-server',path.resolve(__dirname, 'app/main.js')],
  output: {
    path: path.resolve(__dirname, 'build'),
    filename: 'bundle.js'
  },
  module: {
      loaders: [
          { test: /\.js$/, exclude: /node_modules/, loader: "babel-loader"}
      ]
  }
};

Here is my app/main.js

var React = require("react");
React.render(<h1>hello world</h1>,document.getElementById("app"));

And this is the error message

ERROR in ./app/main.js
Module build failed: SyntaxError: ~/**/app/main.js: Unexpected token (2:13)
  1 | var React = require("react");
> 2 | React.render(<h1>hello world</h1>,document.getElementById("app"));
    |              ^
at Parser.pp.raise (~/**/node_modules/babylon/lib/parser/location.js:24:13)

Thanks for you guys.

Answer 1

Add "babel-preset-react"

npm install babel-preset-react

and add "presets" option to babel-loader in your webpack.config.js

(or you can add it to your .babelrc or package.js: http://babeljs.io/docs/usage/babelrc/)

Here is an example webpack.config.js:

{ 
    test: /\.jsx?$/,         // Match both .js and .jsx files
    exclude: /node_modules/, 
    loader: "babel", 
    query:
      {
        presets:['react']
      }
}

Recently Babel 6 was released and there was a major change: https://babeljs.io/blog/2015/10/29/6.0.0

If you are using react 0.14, you should use ReactDOM.render() (from require('react-dom')) instead of React.render(): https://facebook.github.io/react/blog/#changelog

UPDATE 2018

Rule.query has already been deprecated in favour of Rule.options. Usage in webpack 4 is as follows:

npm install babel-loader babel-preset-react

Then in your webpack configuration (as an entry in the module.rules array in the module.exports object)

{
    test: /\.jsx?$/,
    exclude: /node_modules/,
    use: [
      {
        loader: 'babel-loader',
        options: {
          presets: ['react']
        }
      }
    ],
  }

Answer 2

I ran into a similar issue when migrating from babel 5 to babel 6.

I was just running babel to compile the src to lib folder babel src --out-dir lib

I will share my setup for babel 6:

Ensure you have the following babel 6 devDependencies installed

"babel-core": "^6.7.6",
"babel-loader": "^6.2.4",
"babel-preset-es2015": "^6.6.0",
"babel-preset-react": "^6.5.0",
"babel-preset-stage-0": "^6.5.0"

Add your .babelrc file to the project:

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

Answer 3

Since the answer above still leaves some people in the dark, here's what a complete webpack.config.js might look like:

var path = require('path');
var config = {
    entry: path.resolve(__dirname, 'app/main.js'),
    output: {
        path: path.resolve(__dirname, 'build'),
        filename: 'bundle.js'
    },
    module: {
        loaders: [{
            test: /\.jsx?$/,
            loader: 'babel',
            query:
            {
                presets:['es2015', 'react']
            }
        }]
    },

};

module.exports = config;