array.mapFilterreduce.js

let persons = [
   { name: 'John', age: 25, gender: 'male'},
   { name: 'Doe',  age: 35, gender: 'male'},
   { name: 'Nayla',age: 18, gender: 'female'},
   { name: 'Alex', age: 21, gender: 'female'}, 
   { name: 'Jane', age: 22, gender: 'male'}
];

let age = persons.filter((person)=>{
  return person.gender === 'male';
}).map((person)=>{
  return person.age + 5;
}).reduce((sum,age)=>{
  return sum + age;
});
console.log(age); /// 97