Babel-loader jsx SyntaxError: Unexpected token

Breaking down the bug

The problem here is a misconfiguration or lack of appropriate presets in your Babel setup. It signifies that Babel is having a hard time understanding your JSX syntax and is tossing an unexpected token error during the transpilation process. This often occurs when you ambitiously try to use JSX in .js files without informing Babel.

Setting stage: Configuring webpack and babel-loader

Update webpack with babel-loader

Start by teaching your webpack configuration to speak babel-loader fluently:

module: {
  rules: [
    {
      test: /\.(js|jsx)$/,  // Tell webpack to test for .js or .jsx files
      exclude: /node_modules/,  // exclude the node_modules directory
      use: {
        loader: 'babel-loader', // Use babel-loader for these files
        options: {
          presets: ['@babel/preset-env', '@babel/preset-react']  // Make sure Babel understands env and react.
        }
      }
    }
  ]
}
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The .babelrc config file

Send Babel a clear message by updating/creating a .babelrc file in your project's root:

{
  "presets": ["@babel/preset-env", "@babel/preset-react", "@babel/preset-stage-0"]
}


Keep in mind that including @babel/preset-stage-0 allows you to use experimental JavaScript features that are still having their coffee and figuring out life.

Compatibility composure

Keep your compatibility in check. Make sure your babel-loader version is holding hands with your webpack version:

npm install [email protected] --save-dev


Spicing up your development

For preserving state during hot-reloads in development, give react-hot-loader a try:

npm install react-hot-loader --save-dev


Make it officially a part of your team by adding it to your .babelrc plugins array.

Embarking on the troubleshooting journey

Babel runtime and plugins

At times, the culprit might sneak in from @babel/runtime or other plugins. Investigate with:

npm install @babel/runtime --save
npm install @babel/plugin-transform-runtime --save-dev


Seal the deal by appending the latter plugin to your .babelrc.

In search for syntax errors

Keep a sharp eye for JSX syntax errors lurking in your main.js or entry point file—these could lead to silent issues.

webpack.config.js

Be kind to your webpack.config.js by always excluding the node_modules directory. You don’t want to get lost transpiling dependencies.

React syntax saga

Ensure that you're in sync with the times and using ReactDOM.render() instead of the deprecated React.render(). The latter won't play well with newer React versions.

Deep-dive troubleshooting

When the bug resists

Sometimes, this bug stubbornly refuses to go away. In such times:

• Double-check webpack.config.js for typos or misconfigurations—even machines overlook sometimes.
• Ensure no unrelated presets or plugins are crashing the .babelrc party.
• Relieve yourself from cache torment: npm run clear-cache or remove node_modules and reinstall packages.

Battling integration complications

In the battle arena of multiple tools integration or challenging monorepo setups, ensure everyone speaks the same language when it comes to versions and configs.