source-map-loader

Extracts source maps from existing source files (from their sourceMappingURL).

Getting Started

To begin, you'll need to install source-map-loader:

npm i -D source-map-loader

Then add the plugin to your webpack config. For example:

file.js

import css from 'file.css';

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.js$/,
        enforce: 'pre',
        use: ['source-map-loader'],
      },
    ],
  },
};

source-map-loader extracts existing source maps from all JavaScript entries. This includes both inline source maps as well as those linked via URL. All source map data is passed to webpack for processing as per a chosen source map style specified by the devtool option in webpack.config.js. This loader is especially useful when using 3rd-party libraries having their own source maps. If not extracted and processed into the source map of the webpack bundle, browsers may misinterpret source map data. source-map-loader allows webpack to maintain source map data continuity across libraries so ease of debugging is preserved. source-map-loader will extract from any JavaScript file, including those in the node_modules directory. Be mindful in setting include and exclude rule conditions to maximize bundling performance.

And run webpack via your preferred method.

Examples

Ignoring Warnings

To ignore warnings, you can use the following configuration:

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.js$/,
        enforce: 'pre',
        use: ['source-map-loader'],
      },
    ],
  },
  stats: {
    warningsFilter: [/Failed to parse source map/],
  },
};

More information about the warningsFilters option you can find here;

Skipping files

You can provide custom callback function skipResource in order to instruct source-map-loader to skip processing of any source map it will find. To do that, pass the function as the loader option. Function receives two arguments: loader context object (as defined in (webpack reference)[https://webpack.js.org/api/loaders/#the-loader-context]) and the source map url found in file. Function should return a truthful value if processing source map for the file should be skipped. Source map url is the string which may be an absolute file path, relative file path, file url, http url or data url.

Example configuration:

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.js$/,
        enforce: 'pre',
        use: [
          {
            skipResource: (loaderContext, url) => {
              // Load source map only for files in package "my-package"
              return loaderContext.context.match(/node_modules[\\/]my-package/);
            },
          },
        ],
      },
    ],
  },
};

Contributing

Please take a moment to read our contributing guidelines if you haven't yet done so.

CONTRIBUTING

License

MIT