合并重复并增加JavaScript中数组中每个对象的计数
假设我们有一个像这样的对象数组-
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"}
];我们需要编写一个JavaScript函数，该函数接受一个这样的对象数组。该函数应计算数组中重复对象的数量（基于对象的“code”属性），并为每个唯一对象分配一个新的count属性。
如果年龄（使用“DOB”和当前日期计算）小于18岁，则该函数还应为每个唯一对象分配一个子属性，其值将为1，否则为0。
示例
为此的代码将是-
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));输出结果
控制台中的输出将是-
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 }
}