gengitkan/client/src/store/selectors/boards.js

export function selectBoardByUserProjects(boardsByID, projectsByName) {
  const userProjects = Object.keys(projectsByName);
  return Object.keys(boardsByID).reduce((filteredBoardsByID, boardID) => {
    const board = boardsByID[boardID];
    const hasProject = board.projects.length === 0 || board.projects.some(p => userProjects.indexOf(p) !== -1);
    if (hasProject) {
      filteredBoardsByID[boardID] = board;
    }
    return filteredBoardsByID;
  }, {});
}