Cho mảng đối tượng {code, gender, DOB}. Gom theo code, đếm count, đếm female, xác định child (tuổi < 18).
Ví dụ
const arr = [ {code: "AA", gender:"male", DOB:"2000−05−15"}, {code: "AA", gender:"female", DOB:"2015−05−15"}, {code:"A0", gender:"female", DOB:"2005−01−01"}, {code: "A1", gender:"male", DOB:"2015−01−15"} ]; const groupAndAdd = (arr = []) => { const result = new Map(); let nowYear = new Date().getYear(); arr.forEach(el => { let item = result.get(el.code) || {code: el.code, count: 0, female: 0, child: 0 }; item.count++; item.female += el.gender === "female"; item.child += nowYear − new Date(Date.parse(el.DOB)).getYear() <18; result.set(item.code, item); }); return result; }; console.log(groupAndAdd(arr));
Kết quả
Map { 'AA' => { code: 'AA', count: 2, female: 1, child: 1 }, 'A0' => { code: 'A0', count: 1, female: 1, child: 1 }, 'A1' => { code: 'A1', count: 1, female: 0, child: 1 } }