[Alexandroppolus]

function getPagesArr(pages, categories) {
  var map = categories.reduce((m, c) => (m.set(c._id, c.catClass), m), new Map());
  return pages.map((p) => {
    var v = Object.assign({}, p);
    v.ctgrId = map.get(p.ctgrId) || p.ctgrId;
    return v;
  });
}