Cho mảng đối tượng {location, identity_long}. Gom nhóm theo cặp (location, identity), thêm count.
Ví dụ
const arr = [ {"location":"Kirrawee","identity_long":"student"}, {"location":"Kirrawee","identity_long":"visitor"}, {"location":"Kirrawee","identity_long":"visitor"}, {"location":"Kirrawee","identity_long":"worker"}, {"location":"Sutherland","identity_long":"student"}, {"location":"Sutherland","identity_long":"resident"}, {"location":"Sutherland","identity_long":"worker"}, {"location":"Sutherland","identity_long":"resident"}, {"location":"Miranda","identity_long":"resident"}, {"location":"Miranda","identity_long":"worker"}, {"location":"Miranda","identity_long":"student"}, {"location":"Miranda","identity_long":""}, {"location":"Miranda","identity_long":"worker"}, {"location":"Miranda","identity_long":"resident"} ]; const groupArray = (arr = []) => { let map = new Map() for (let i = 0; i < arr.length; i++) { const s = JSON.stringify(arr[i]); if (!map.has(s)) { map.set(s, { location: arr[i].location, identity: arr[i].identity_long, count: 1, }); } else { map.get(s).count++; } } const res = Array.from(map.values()) return res; }; console.log(groupArray(arr));
Kết quả
[ { location: 'Kirrawee', identity: 'student', count: 1 }, { location: 'Kirrawee', identity: 'visitor', count: 2 }, { location: 'Kirrawee', identity: 'worker', count: 1 }, { location: 'Sutherland', identity: 'student', count: 1 }, { location: 'Sutherland', identity: 'resident', count: 2 }, { location: 'Sutherland', identity: 'worker', count: 1 }, { location: 'Miranda', identity: 'resident', count: 2 }, { location: 'Miranda', identity: 'worker', count: 2 }, { location: 'Miranda', identity: 'student', count: 1 }, { location: 'Miranda', identity: '', count: 1 } ]