supportWebpack4.js

import {
  workerGenerator,
  sourceMappingURLRegex,
  sourceURLWebpackRegex,
} from "./utils";

export default function runAsChild(
  loaderContext,
  workerContext,
  options,
  callback
) {
  workerContext.compiler.runAsChild((error, entries, compilation) => {
    if (error) {
      return callback(error);
    }

    if (entries[0]) {
      // eslint-disable-next-line no-param-reassign, prefer-destructuring
      const workerFilename = entries[0].files[0];

      let workerSource = compilation.assets[workerFilename].source();

      if (options.inline === "no-fallback") {
        // eslint-disable-next-line no-underscore-dangle, no-param-reassign
        delete loaderContext._compilation.assets[workerFilename];

        // TODO improve it, we should store generated source maps files for file in `assetInfo`
        // eslint-disable-next-line no-underscore-dangle
        if (loaderContext._compilation.assets[`${workerFilename}.map`]) {
          // eslint-disable-next-line no-underscore-dangle, no-param-reassign
          delete loaderContext._compilation.assets[`${workerFilename}.map`];
        }

        // Remove `/* sourceMappingURL=url */` comment
        workerSource = workerSource.replace(sourceMappingURLRegex, "");

        // Remove `//# sourceURL=webpack-internal` comment
        workerSource = workerSource.replace(sourceURLWebpackRegex, "");
      }

      const workerCode = workerGenerator(
        loaderContext,
        workerFilename,
        workerSource,
        options
      );

      return callback(null, workerCode);
    }

    return callback(
      new Error(
        `Failed to compile web worker "${workerContext.request}" request`
      )
    );
  });
}