code: function isCssClassMatching(nodeClassAttrVal, cssClassToMatch) {
      var nodeClassesLen = nodeClassAttrVal.length;
      var matchIndex = nodeClassAttrVal.indexOf(cssClassToMatch);
      var matchEndIdx = matchIndex + cssClassToMatch.length;
      if (matchIndex === -1 // no match
          || (matchIndex > 0 && nodeClassAttrVal[matchIndex - 1] !== ' ') // no space before
          ||
              (matchEndIdx < nodeClassesLen && nodeClassAttrVal[matchEndIdx] !== ' ')) // no space after
       {
          return false;
      }
      return true;
  }
docs: @license
  Copyright Google Inc. All Rights Reserved.
  
  Use of this source code is governed by an MIT-style license that can be
  found in the LICENSE file at https://angular.io/license