index.js

import path from 'path';

import { SourceMapConsumer } from 'source-map';
import { SourceMapSource, RawSource, ConcatSource } from 'webpack-sources';
import RequestShortener from 'webpack/lib/RequestShortener';
import {
  ModuleFilenameHelpers,
  SourceMapDevToolPlugin,
  javascript,
  version as webpackVersion,
} from 'webpack';
import createHash from 'webpack/lib/util/createHash';
import validateOptions from 'schema-utils';
import serialize from 'serialize-javascript';
import terserPackageJson from 'terser/package.json';

import schema from './options.json';
import TaskRunner from './TaskRunner';

const warningRegex = /\[.+:([0-9]+),([0-9]+)\]/;

class TerserPlugin {
  constructor(options = {}) {
    validateOptions(schema, options, {
      name: 'Terser Plugin',
      baseDataPath: 'options',
    });

    const {
      minify,
      terserOptions = {},
      test = /\.m?js(\?.*)?$/i,
      chunkFilter = () => true,
      warningsFilter = () => true,
      extractComments = true,
      sourceMap,
      cache = true,
      cacheKeys = (defaultCacheKeys) => defaultCacheKeys,
      parallel = true,
      include,
      exclude,
    } = options;

    this.options = {
      test,
      chunkFilter,
      warningsFilter,
      extractComments,
      sourceMap,
      cache,
      cacheKeys,
      parallel,
      include,
      exclude,
      minify,
      terserOptions,
    };
  }

  static isSourceMap(input) {
    // All required options for `new SourceMapConsumer(...options)`
    // https://github.com/mozilla/source-map#new-sourcemapconsumerrawsourcemap
    return Boolean(
      input &&
        input.version &&
        input.sources &&
        Array.isArray(input.sources) &&
        typeof input.mappings === 'string'
    );
  }

  static buildSourceMap(inputSourceMap) {
    if (!inputSourceMap || !TerserPlugin.isSourceMap(inputSourceMap)) {
      return null;
    }

    return new SourceMapConsumer(inputSourceMap);
  }

  static buildError(error, file, sourceMap, requestShortener) {
    // Handling error which should have line, col, filename and message
    if (error.line) {
      const original =
        sourceMap &&
        sourceMap.originalPositionFor({
          line: error.line,
          column: error.col,
        });

      if (original && original.source && requestShortener) {
        return new Error(
          `${file} from Terser\n${error.message} [${requestShortener.shorten(
            original.source
          )}:${original.line},${original.column}][${file}:${error.line},${
            error.col
          }]${
            error.stack
              ? `\n${error.stack
                  .split('\n')
                  .slice(1)
                  .join('\n')}`
              : ''
          }`
        );
      }

      return new Error(
        `${file} from Terser\n${error.message} [${file}:${error.line},${
          error.col
        }]${
          error.stack
            ? `\n${error.stack
                .split('\n')
                .slice(1)
                .join('\n')}`
            : ''
        }`
      );
    }

    if (error.stack) {
      return new Error(`${file} from Terser\n${error.stack}`);
    }

    return new Error(`${file} from Terser\n${error.message}`);
  }

  static buildWarning(
    warning,
    file,
    sourceMap,
    requestShortener,
    warningsFilter
  ) {
    let warningMessage = warning;
    let locationMessage = '';
    let source = null;

    if (sourceMap) {
      const match = warningRegex.exec(warning);

      if (match) {
        const line = +match[1];
        const column = +match[2];
        const original = sourceMap.originalPositionFor({
          line,
          column,
        });

        if (
          original &&
          original.source &&
          original.source !== file &&
          requestShortener
        ) {
          ({ source } = original);
          warningMessage = `${warningMessage.replace(warningRegex, '')}`;

          locationMessage = `[${requestShortener.shorten(original.source)}:${
            original.line
          },${original.column}]`;
        }
      }
    }

    // Todo change order in next major release
    if (warningsFilter && !warningsFilter(warning, source, file)) {
      return null;
    }

    return `Terser Plugin: ${warningMessage}${locationMessage}`;
  }

  static removeQueryString(filename) {
    let targetFilename = filename;

    const queryStringIdx = targetFilename.indexOf('?');

    if (queryStringIdx >= 0) {
      targetFilename = targetFilename.substr(0, queryStringIdx);
    }

    return targetFilename;
  }

  static hasAsset(commentFilename, assets) {
    const assetFilenames = Object.keys(assets).map((assetFilename) =>
      TerserPlugin.removeQueryString(assetFilename)
    );

    return assetFilenames.includes(
      TerserPlugin.removeQueryString(commentFilename)
    );
  }

  static isWebpack4() {
    return webpackVersion[0] === '4';
  }

  *taskGenerator(compiler, compilation, allExtractedComments, file) {
    let inputSourceMap;

    const asset = compilation.assets[file];

    try {
      let input;

      if (this.options.sourceMap && asset.sourceAndMap) {
        const { source, map } = asset.sourceAndMap();

        input = source;

        if (TerserPlugin.isSourceMap(map)) {
          inputSourceMap = map;
        } else {
          inputSourceMap = map;

          compilation.warnings.push(
            new Error(`${file} contains invalid source map`)
          );
        }
      } else {
        input = asset.source();
        inputSourceMap = null;
      }

      // Handling comment extraction
      let commentsFilename = false;

      if (this.options.extractComments) {
        commentsFilename =
          this.options.extractComments.filename || '[file].LICENSE.txt[query]';

        if (TerserPlugin.isWebpack4()) {
          // Todo remove this in next major release
          if (typeof commentsFilename === 'function') {
            commentsFilename = commentsFilename.bind(null, file);
          }
        }

        let query = '';
        let filename = file;

        const querySplit = filename.indexOf('?');

        if (querySplit >= 0) {
          query = filename.substr(querySplit);
          filename = filename.substr(0, querySplit);
        }

        const lastSlashIndex = filename.lastIndexOf('/');

        const basename =
          lastSlashIndex === -1
            ? filename
            : filename.substr(lastSlashIndex + 1);

        const data = { filename, basename, query };

        commentsFilename = compilation.getPath(commentsFilename, data);
      }

      if (
        commentsFilename &&
        TerserPlugin.hasAsset(commentsFilename, compilation.assets)
      ) {
        // Todo make error and stop uglifing in next major release
        compilation.warnings.push(
          new Error(
            `The comment file "${TerserPlugin.removeQueryString(
              commentsFilename
            )}" conflicts with an existing asset, this may lead to code corruption, please use a different name`
          )
        );
      }

      const callback = (taskResult) => {
        const { error, map, code, warnings } = taskResult;
        const { extractedComments } = taskResult;

        let sourceMap = null;

        if (error || (warnings && warnings.length > 0)) {
          sourceMap = TerserPlugin.buildSourceMap(inputSourceMap);
        }

        // Handling results
        // Error case: add errors, and go to next file
        if (error) {
          compilation.errors.push(
            TerserPlugin.buildError(
              error,
              file,
              sourceMap,
              new RequestShortener(compiler.context)
            )
          );

          return;
        }

        let outputSource;

        if (map) {
          outputSource = new SourceMapSource(
            code,
            file,
            map,
            input,
            inputSourceMap,
            true
          );
        } else {
          outputSource = new RawSource(code);
        }

        // Write extracted comments to commentsFilename
        if (
          commentsFilename &&
          extractedComments &&
          extractedComments.length > 0
        ) {
          if (!allExtractedComments[commentsFilename]) {
            // eslint-disable-next-line no-param-reassign
            allExtractedComments[commentsFilename] = [];
          }

          // eslint-disable-next-line no-param-reassign
          allExtractedComments[commentsFilename] = allExtractedComments[
            commentsFilename
          ].concat(extractedComments);

          // Add a banner to the original file
          if (this.options.extractComments.banner !== false) {
            let banner =
              this.options.extractComments.banner ||
              `For license information please see ${path
                .relative(path.dirname(file), commentsFilename)
                .replace(/\\/g, '/')}`;

            if (typeof banner === 'function') {
              banner = banner(commentsFilename);
            }

            if (banner) {
              outputSource = new ConcatSource(
                `/*! ${banner} */\n`,
                outputSource
              );
            }
          }
        }

        // Updating assets
        // eslint-disable-next-line no-param-reassign
        compilation.assets[file] = outputSource;

        // Handling warnings
        if (warnings && warnings.length > 0) {
          warnings.forEach((warning) => {
            const builtWarning = TerserPlugin.buildWarning(
              warning,
              file,
              sourceMap,
              new RequestShortener(compiler.context),
              this.options.warningsFilter
            );

            if (builtWarning) {
              compilation.warnings.push(builtWarning);
            }
          });
        }
      };

      const task = {
        asset,
        file,
        input,
        inputSourceMap,
        commentsFilename,
        extractComments: this.options.extractComments,
        terserOptions: this.options.terserOptions,
        minify: this.options.minify,
        callback,
      };

      if (TerserPlugin.isWebpack4()) {
        if (this.options.cache) {
          const defaultCacheKeys = {
            terser: terserPackageJson.version,
            // eslint-disable-next-line global-require
            'terser-webpack-plugin': require('../package.json').version,
            'terser-webpack-plugin-options': this.options,
            nodeVersion: process.version,
            filename: file,
            contentHash: TerserPlugin.getHasher(compiler)
              .update(input)
              .digest('hex'),
          };

          task.cacheKeys = this.options.cacheKeys(defaultCacheKeys, file);
        }
      } else {
        task.cacheKeys = {
          terser: terserPackageJson.version,
          // eslint-disable-next-line global-require
          'terser-webpack-plugin': require('../package.json').version,
          'terser-webpack-plugin-options': this.options,
        };
      }

      yield task;
    } catch (error) {
      compilation.errors.push(
        TerserPlugin.buildError(
          error,
          file,
          TerserPlugin.buildSourceMap(inputSourceMap),
          new RequestShortener(compiler.context)
        )
      );
    }
  }

  apply(compiler) {
    const { devtool, output, plugins } = compiler.options;

    this.options.sourceMap =
      typeof this.options.sourceMap === 'undefined'
        ? (devtool &&
            !devtool.includes('eval') &&
            !devtool.includes('cheap') &&
            (devtool.includes('source-map') ||
              // Todo remove when `webpack@5` support will be dropped
              devtool.includes('sourcemap'))) ||
          (plugins &&
            plugins.some(
              (plugin) =>
                plugin instanceof SourceMapDevToolPlugin &&
                plugin.options &&
                plugin.options.columns
            ))
        : Boolean(this.options.sourceMap);

    if (
      typeof this.options.terserOptions.module === 'undefined' &&
      typeof output.module !== 'undefined'
    ) {
      this.options.terserOptions.module = output.module;
    }

    if (
      typeof this.options.terserOptions.ecma === 'undefined' &&
      typeof output.ecmaVersion !== 'undefined'
    ) {
      this.options.terserOptions.ecma = output.ecmaVersion;
    }

    const optimizeFn = async (compilation, chunks) => {
      const matchObject = ModuleFilenameHelpers.matchObject.bind(
        // eslint-disable-next-line no-undefined
        undefined,
        this.options
      );
      const files = []
        .concat(Array.from(compilation.additionalChunkAssets || []))
        .concat(
          Array.from(chunks)
            .filter(
              (chunk) =>
                this.options.chunkFilter && this.options.chunkFilter(chunk)
            )
            .reduce(
              (acc, chunk) => acc.concat(Array.from(chunk.files || [])),
              []
            )
        )
        .filter((file) => matchObject(file));

      if (files.length === 0) {
        return Promise.resolve();
      }

      const CacheEngine = TerserPlugin.isWebpack4()
        ? // eslint-disable-next-line global-require
          require('./Webpack4Cache').default
        : // eslint-disable-next-line global-require
          require('./Webpack5Cache').default;

      const allExtractedComments = {};
      const taskGenerator = this.taskGenerator.bind(
        this,
        compiler,
        compilation,
        allExtractedComments
      );
      const taskRunner = new TaskRunner({
        taskGenerator,
        files,
        cache: new CacheEngine(compiler, compilation, this.options),
        parallel: this.options.parallel,
      });

      await taskRunner.run();
      await taskRunner.exit();

      Object.keys(allExtractedComments).forEach((commentsFilename) => {
        const extractedComments = new Set([
          ...allExtractedComments[commentsFilename].sort(),
        ]);

        // eslint-disable-next-line no-param-reassign
        compilation.assets[commentsFilename] = new RawSource(
          `${Array.from(extractedComments).join('\n\n')}\n`
        );
      });

      return Promise.resolve();
    };

    const plugin = { name: this.constructor.name };

    compiler.hooks.compilation.tap(plugin, (compilation) => {
      if (this.options.sourceMap) {
        compilation.hooks.buildModule.tap(plugin, (moduleArg) => {
          // to get detailed location info about errors
          // eslint-disable-next-line no-param-reassign
          moduleArg.useSourceMap = true;
        });
      }

      if (!TerserPlugin.isWebpack4()) {
        const hooks = javascript.JavascriptModulesPlugin.getCompilationHooks(
          compilation
        );
        const data = serialize({
          terser: terserPackageJson.version,
          terserOptions: this.options.terserOptions,
        });

        hooks.chunkHash.tap(plugin, (chunk, hash) => {
          hash.update('TerserPlugin');
          hash.update(data);
        });
      } else {
        // Todo remove after drop `webpack@4` compatibility
        const { mainTemplate, chunkTemplate } = compilation;
        const data = serialize({
          terser: terserPackageJson.version,
          terserOptions: this.options.terserOptions,
        });

        // Regenerate `contenthash` for minified assets
        for (const template of [mainTemplate, chunkTemplate]) {
          template.hooks.hashForChunk.tap(plugin, (hash) => {
            hash.update('TerserPlugin');
            hash.update(data);
          });
        }
      }

      compilation.hooks.optimizeChunkAssets.tapPromise(
        plugin,
        optimizeFn.bind(this, compilation)
      );
    });
  }

  static getHasher(compiler = null) {
    const hashFunction =
      compiler && compiler.output && compiler.output.hashFunction;

    return createHash(hashFunction || 'md4');
  }
}

export default TerserPlugin;