api.js

/*
  MIT License http://www.opensource.org/licenses/mit-license.php
  Author Tobias Koppers @sokra
*/
// css base code, injected by the css-loader
module.exports = function(useSourceMap) {
  var list = [];

  // return the list of modules as css string
  list.toString = function toString() {
    return this.map(function(item) {
      var content = cssWithMappingToString(item, useSourceMap);
      if (item[2]) {
        return '@media ' + item[2] + '{' + content + '}';
      } else {
        return content;
      }
    }).join('');
  };

  // import a list of modules into the list
  list.i = function(modules, mediaQuery) {
    if (typeof modules === 'string') {
      modules = [[null, modules, '']];
    }
    var alreadyImportedModules = {};
    for (var i = 0; i < this.length; i++) {
      var id = this[i][0];
      if (id != null) {
        alreadyImportedModules[id] = true;
      }
    }
    for (i = 0; i < modules.length; i++) {
      var item = modules[i];
      // skip already imported module
      // this implementation is not 100% perfect for weird media query combinations
      // when a module is imported multiple times with different media queries.
      // I hope this will never occur (Hey this way we have smaller bundles)
      if (item[0] == null || !alreadyImportedModules[item[0]]) {
        if (mediaQuery && !item[2]) {
          item[2] = mediaQuery;
        } else if (mediaQuery) {
          item[2] = '(' + item[2] + ') and (' + mediaQuery + ')';
        }
        list.push(item);
      }
    }
  };
  return list;
};

function cssWithMappingToString(item, useSourceMap) {
  var content = item[1] || '';
  var cssMapping = item[3];
  if (!cssMapping) {
    return content;
  }

  if (useSourceMap && typeof btoa === 'function') {
    var sourceMapping = toComment(cssMapping);
    var sourceURLs = cssMapping.sources.map(function(source) {
      return '/*# sourceURL=' + cssMapping.sourceRoot + source + ' */';
    });

    return [content]
      .concat(sourceURLs)
      .concat([sourceMapping])
      .join('\n');
  }

  return [content].join('\n');
}

// Adapted from convert-source-map (MIT)
function toComment(sourceMap) {
  // eslint-disable-next-line no-undef
  var base64 = btoa(unescape(encodeURIComponent(JSON.stringify(sourceMap))));
  var data =
    'sourceMappingURL=data:application/json;charset=utf-8;base64,' + base64;

  return '/*# ' + data + ' */';
}