Function extractText

packages/extract-text/index.js:15–53

* @param {string} outputFilePattern * @return {Function}

(outputFilePattern = 'css/[name].[contenthash:8].css')

 * @return {Function}
 */
function extractText(outputFilePattern = 'css/[name].[contenthash:8].css') {
  const plugin = new ExtractTextPlugin(outputFilePattern)

  const postHook = (context, util) => prevConfig => {
    let nextConfig = prevConfig

    // Only apply to loaders in the same `match()` group or css loaders if there is no `match()`
    const ruleToMatch = context.match || { test: /\.css$/ }
    const matchingLoaderRules = getMatchingLoaderRules(ruleToMatch, prevConfig)

    if (matchingLoaderRules.length === 0) {
      throw new Error(
        `extractText(): No loaders found to extract contents from. Looking for loaders matching ${
          ruleToMatch.test
        }`
      )
    }

    const [fallbackLoaders, nonFallbackLoaders] = splitFallbackRule(matchingLoaderRules)

    const newLoaderDef = Object.assign({}, ruleToMatch, {
      use: plugin.extract({
        fallback: fallbackLoaders,
        use: nonFallbackLoaders
      })
    })

    for (const ruleToRemove of matchingLoaderRules) {
      nextConfig = removeLoaderRule(ruleToRemove)(nextConfig)
    }

    nextConfig = util.addPlugin(plugin)(nextConfig)
    nextConfig = util.addLoader(newLoaderDef)(nextConfig)

    return nextConfig
  }

  return Object.assign(() => prevConfig => prevConfig, { post: postHook })
}

function getMatchingLoaderRules(ruleToMatch, webpackConfig) {
  return webpackConfig.module.rules.filter(