How to add a query to a webpack loader with multip

问题:

I have this Babel loader that's working

{ test: /\.jsx?$/, loader: 'babel', query: babelSettings, exclude: /node_modules/ },

But now I want a CoffeeScript loader but I want to pipe it through Babel to get the the fancy HMR stuff

{ test: /\.coffee$/, loader: 'babel!coffee', query: babelSettings, exclude: /node_modules/ },

This doesn't work though, and results in the following error.

Error: Cannot define 'query' and multiple loaders in loaders list

Any idea how to define the query just for the Babel part of the loader chain? The query is a complicated object and I don't think I can encode it.

var babelSettings = { stage: 0 };

if (process.env.NODE_ENV !== 'production') {
  babelSettings.plugins = ['react-transform'];
  babelSettings.extra = {
    'react-transform': {
      transforms: [{
        transform: 'react-transform-hmr',
        imports: ['react'],
        locals: ['module']
      }, {
        transform: 'react-transform-catch-errors',
        imports: ['react', 'redbox-react']
      }]
      // redbox-react is breaking the line numbers :-(
      // you might want to disable it
    }
  };
}

回答1:

The way to do this is to set the query parameters in the loader string itself, as the query object key will only work for one loader.

Assuming your settings object can be serialized to JSON, as your example indicates, you could easily pass your settings object as a JSON query. Then only the Babel loader will get the settings.

{ test: /\.coffee$/, loader: 'babel?'+JSON.stringify(babelSettings)+'!coffee', exclude: /node_modules/ }

The feature for doing this is somewhat documented here:

Using Loaders: Query parameters

Most loaders accept parameters in the normal query format (?key=value&key2=value2) and as JSON object (?{"key":"value","key2":"value2"}).

回答2:

Sokra, the creator of Webpack, gives his own take on how to do this here, but you'll probably be better served with the webpack-combine-loaders helper that's more similar in style to defining a single loader with the query object.

With webpack-combine-loaders, you can define multiple loaders as such:

combineLoaders([
  {
    loader: 'css-loader',
    query: {
      modules: true,
      sourceMap: true,
      localIdentName: '[name]__[local]--[hash:base64:5]',
    },
  },
  {
    loader: 'sass-loader',
    query: {
      sourceMap: true,
      includePaths: [
        'app/assets/stylesheets',
        'app/assets/stylesheets/legacy',
      ],
    },
  },
]);

回答3:

In webpack 2 & 3 this can be configured much more cleanly.

Loaders can be passed in an array of loader objects. Each loader object can specify an options object that acts like the webpack 1 query for that particular loader.

For example, using both react-hot-loader and babel-loader, with babel-loader configured with some options, in webpack 2 & 3

module: {
  rules: [{
    test: /\.js$/,
    exclude: /node_modules/,
    use: [{
      loader: 'react-hot-loader'
    }, {
      loader: 'babel-loader',
      options: {
        babelrc: false,
        presets: [
          'es2015-native-modules',
          'stage-0',
          'react'
        ]
      }
    }]
  }] 
}

For comparison, here is the same configuration in webpack 1, using the query string method.

module: {
  loaders: [{
    test: /\.js$/,
    exclude: /node_modules/,
    loaders: [
      'react-hot',
      'babel-loader?' +
        'babelrc=false,' +
        'presets[]=es2015,' +
        'presets[]=stage-0,' +
        'presets[]=react'
      ]
  }] 
}

Notice the changed property names all down the chain.

Also, note that I changed the es2015 preset to es2015-native-modules preset in the babel-loader configuration. This has nothing to do with the specification of options, it's just that including es6 modules allows you to use the tree-shaking feature introduced in v2. It could be left alone and it would still work, but the answer would feel incomplete without that obvious upgrade being pointed out :-)

回答4:

The test property is just regex, so you can run a check for both jsx and coffee at the same time: test: /\.(jsx|coffee)$/

Sass/SCSS is a little easier: test: /\.s[ac]ss$/