exercise with reduce

reduce_ex.js

mocha.setup('bdd');

var expect = chai.expect;

const employees = [
  { name: "Barak Obama", role: "president", pay: 35000 },
  { name: "Noa Kirel", role: "artist", pay: 1000000 },
  { name: "Donald Trump", role: "president", pay: 40000 },
  { name: "Tova Cohen", role: "teacher", pay: 135210 },
  { name: "Ivri Lider", role: "artist", pay: 32000 },
  { name: "Dan Bilzarian", role: "player", pay: 12000000 },
  { name: "Roni Levi", role: "teacher", pay: 51000 },
];

function findMax() {
  // return name and pay of max paid employee
  return employees.reduce((a, b) => {
  	return a.pay > b.pay ? a : b
  })
}

function findAverage() {
  // return average pay
  const length = employees.length;
  const sum = employees.reduce((acc, curr) => {
  	return acc + curr.pay;
  }, 0);
  
  return sum / length;
}

function averageByRole() {
  // return an object {[role]: average pay per role}
   const obj = employees.reduce((acc, curr) => {
   acc[curr.role] = acc[curr.role] || {role: curr.role, pay: 0, count: 0};
   acc[curr.role].count += 1
   acc[curr.role].pay += curr.pay
   return acc;
   }, {})
   
   for(key in obj) {
     obj[key] = obj[key].pay / obj[key].count
   }
  return obj;
}

console.log(averageByRole())



describe('find max', () => {
  it('should return name and pay of highest paid employee', () => {
    const max = findMax();

    expect(max.pay).to.equal(12000000);
    expect(max.name).to.equal("Dan Bilzarian");
  });
});

describe('find average', () => {
  it('should return average salary', () => {
    const averageSalary = findAverage();

    expect(averageSalary).to.equal(1899030);
  });
});


describe('average by role', () => {
  it('should return object with average pay per role', () => {
    const averageSalaryByRole = averageByRole();

    expect(averageSalaryByRole).to.deep.equal({
      artist: 516000,
      player: 12000000,
      president: 37500,
      teacher: 93105
    });
  });
});

mocha.run();