I have an array of objects as follows :
let people = [
{ name: "Emily", age: 15 }, { name: "Emma", age: 16 },
{ name: "Stacy", age: 18 }, { name: "Emily", age: 15 },
{ name: "Jennifer", age: 12 }
];
I need to return the result containing the age as the key and frequency as it's corresponding value as follows :
{ 15 : 2, 16 : 1, 18 : 1, 12 : 1 }
I wish I could implement this using both forEach() and reduce().
Using Array#reduce:
const people = [ { name: "Emily", age: 15 }, { name: "Emma", age: 16 }, { name: "Stacy", age: 18 }, { name: "Emily", age: 15 }, { name: "Jennifer", age: 12 } ];
const ageCount = people.reduce((map, { age }) => ({
...map,
[age]: (map[age] || 0) + 1
}), {});
console.log(ageCount);