grunt helper for finding the longest common path

grunt_common_path.js

grunt.registerHelper('commonPath', function(inFiles) {

  var results = [],
      minLen = 99,
      isValid,
      dirs;

  dirs = inFiles.map(function(filepath) {
    var tmpArr = path.dirname(filepath).split('/');
    if(tmpArr.length < minLen) {
      minLen = tmpArr.length;
    };
    return tmpArr;
  });

  if (dirs.length) {
    for (var _j = 0; _j < minLen; _j++) {
      isValid = true;
      for (var _i = 1, _len = dirs.length; _i < _len; _i++) {
        if(dirs[0][_j] !== dirs[_i][_j]) {
          isValid = false;
          break;
        }
      }
      if(isValid) {
        results.push(dirs[0][_j]);
      } else {
        break;
      }
    }
  };

  return path.join(results.join('/'));

});