exclude node_modules from source map

[sushantdhiman]

Is there a way to exclude a folder from source maps while keeping files in bundle.

Similar issues

• Exclude files from sourcemaps #1227, but I want to ignore entire node_modules folder instead of a single file.
• Exclude vendor files from source map webpack/webpack#2431, for webpack

Background:

My source maps are too big even with sourcesContent: false (I only need stack-traces). Big source maps take some time to load with node --enable-source-maps

[evanw]

Here is a plugin that does what #1227 does but for anything with node_modules in the path:

let plugin = {
  name: 'excludeVendorFromSourceMap',
  setup(build) {
    build.onLoad({ filter: /node_modules/ }, args => {
      return {
        contents: fs.readFileSync(args.path, 'utf8')
          + '\n//# sourceMappingURL=data:application/json;base64,eyJ2ZXJzaW9uIjozLCJzb3VyY2VzIjpbIiJdLCJtYXBwaW5ncyI6IkEifQ==',
        loader: 'default',
      }
    })
  },
}

Feel free to customize the plugin further for your needs. You can read more about esbuild plugins here: https://esbuild.github.io/plugins/.

[sushantdhiman]

Thanks, I have modified it to work only on js files and it works great.

const excludeVendorFromSourceMapPlugin = ({ filter }) => ({
  name: 'excludeVendorFromSourceMap',
  setup(build) {
    build.onLoad({ filter }, (args) => {
      if (args.path.endsWith('.js')) {
        return {
          contents:
            readFileSync(args.path, 'utf8') +
            '\n//# sourceMappingURL=data:application/json;base64,eyJ2ZXJzaW9uIjozLCJzb3VyY2VzIjpbIiJdLCJtYXBwaW5ncyI6IkEifQ==',
          loader: 'default',
        };
      }
    });
  },
});

If you don't want to add this to esbuild api, you can close this issue

[evanw]

Yes, I think this makes sense to do as a plugin instead of as part of esbuild's API. Closing.

[zach-betz-hln]

I came here from this comment.

After enabling the --enable-source-maps flag, some of our node apps doubled in memory usage (measured directly after startup).

Using your plugin to make the source map file smaller did the trick to lower memory usage to expected levels 👍

The file went from 9.8mb to 493.1kb. Thank you.

Modified plugin

const excludeVendorFromSourceMapPlugin = {
  name: 'excludeVendorFromSourceMapPlugin',
  setup(build) {
    const emptySourceMapAsBase64 = Buffer.from(JSON.stringify({ version: 3, sources: [''], mappings: 'A' })).toString(
      'base64'
    );
    build.onLoad({ filter: /node_modules.+\.(js|ts)$/ }, (args) => {
      return {
        contents: `${fs.readFileSync(args.path, 'utf8')}\n//# sourceMappingURL=data:application/json;base64,${emptySourceMapAsBase64}`,
        loader: 'default'
      };
    });
  }
};