@tech-wizards/favicons-webpack-plugin/lib/compiler.js

Let webpack generate all your favicons and icons for you

'use strict';
var path = require('path');
var SingleEntryPlugin = require('webpack/lib/SingleEntryPlugin');

module.exports.compileTemplate = function compileTemplate (options, context, compilation) {
  // The entry file is just an empty helper as the dynamic template
  // require is added in "loader.js"
  var outputOptions = {
    filename: options.statsFilename,
    publicPath: compilation.outputOptions.publicPath
  };
  // Create an additional child compiler which takes the template
  // and turns it into an Node.JS html factory.
  // This allows us to use loaders during the compilation
  var compilerName = getCompilerName(context, outputOptions.filename);
  var childCompiler = compilation.createChildCompiler(compilerName, outputOptions);
  childCompiler.context = context;

  var singleEntryPlugin = new SingleEntryPlugin(context, '!!' + require.resolve('./favicons.js') + '?' +
    JSON.stringify({
      outputFilePrefix: options.prefix,
      icons: options.icons,
      background: options.background,
      persistentCache: options.persistentCache,
      appName: options.title
    }) + '!' + options.logo);

  (compilation.hooks ? singleEntryPlugin.apply(childCompiler) : childCompiler.apply(singleEntryPlugin));

  // Fix for "Uncaught TypeError: __webpack_require__(...) is not a function"
  // Hot module replacement requires that every child compiler has its own
  // cache. @see https://github.com/ampedandwired/html-webpack-plugin/pull/179
  // (webpack 4 compliant + back compat)
  (childCompiler.hooks
    ? childCompiler.hooks.compilation.tap.bind(childCompiler.hooks.compilation, 'FaviconsWebpackPluginCompilation')
    : childCompiler.plugin.bind(childCompiler, 'compilation')
  )((compilation) => {
    if (compilation.cache) {
      if (!compilation.cache[compilerName]) {
        compilation.cache[compilerName] = {};
      }
      compilation.cache = compilation.cache[compilerName];
    }
    (compilation.hooks
      ? compilation.hooks.optimizeChunkAssets.tapAsync.bind(compilation.hooks.optimizeChunkAssets, 'FaviconsWebpackPluginOptimizeChunkAssets')
      : compilation.plugin.bind(compilation, 'optimize-chunk-assets')
    )((chunks, callback) => {
      if (!chunks[0]) {
        return callback(compilation.errors[0] || 'Favicons generation failed');
      }
      var resultFile = chunks[0].files[0];
      var resultCode = compilation.assets[resultFile].source();
      var resultJson;
      try {
        /* eslint no-eval:0 */
        var result = eval(resultCode);
        resultJson = JSON.stringify(result);
      } catch (e) {
        return callback(e);
      }
      compilation.assets[resultFile] = {
        source: function () {
          return resultJson;
        },
        size: function () {
          return resultJson.length;
        }
      };
      callback(null);
    });
  });

  // Compile and return a promise
  return new Promise(function (resolve, reject) {
    childCompiler.runAsChild(function (err, entries, childCompilation) {
      if (err) {
        return reject(err);
      }
      // Replace [hash] placeholders in filename
      // In webpack 4 the plugin interface changed, so check for available fns
      var outputName = compilation.mainTemplate.getAssetPath
        ? compilation.mainTemplate.hooks.assetPath.call(outputOptions.filename, {
          hash: childCompilation.hash,
          chunk: entries[0]
        })
        : compilation.mainTemplate.applyPluginsWaterfall(
            'asset-path',
            outputOptions.filename,
          {
            hash: childCompilation.hash,
            chunk: entries[0]
          });
      // Resolve / reject the promise
      if (childCompilation && childCompilation.errors && childCompilation.errors.length) {
        var errorDetails = childCompilation.errors.map(function (error) {
          return error.message + (error.error ? ':\n' + error.error : '');
        }).join('\n');
        reject(new Error('Child compilation failed:\n' + errorDetails));
      } else if (err) {
        reject(err);
      } else {
        resolve({
          outputName: outputName,
          stats: JSON.parse(childCompilation.assets[outputName].source())
        });
      }
    });
  });
};

/**
 * Returns the child compiler name e.g. 'html-webpack-plugin for "index.html"'
 */
function getCompilerName (context, filename) {
  var absolutePath = path.resolve(context, filename);
  var relativePath = path.relative(context, absolutePath);
  return 'favicons-webpack-plugin for "' + (absolutePath.length < relativePath.length ? absolutePath : relativePath) + '"';
}