How to write nested arrays with reduce functions in Javascript

Question

const users=[
  {name: "Julia", age: 20},
  {name: "Jane", age: 30}
];

How can we do that we find summary of ages with reduce() function or others?

Answer 1

You can set accumulator to 0 and in each iteration add the age property of the element to ac and return it.

   
const users=[
   {name: "Julia", age: 20},
   {name: "Jane", age: 30}
];
const sum = users.reduce((ac,a) => ac + a.age,0);
console.log(sum);

Using simple loops it will look like.

const users=[
   {name: "Julia", age: 20},
   {name: "Jane", age: 30}
];
let sum = 0;
for(let i = 0;i<users.length;i++){
  sum += users[i].age
}
console.log(sum)

Answer 2

Sum the value with the accumulator, where as initial value of accumulator is 0

The 0 at the end is the initial value of the accumulator.acc += curr.age will add the age of the each object with accumulator value

const users = [{
    name: "Julia",
    age: 20
  },
  {
    name: "Jane",
    age: 30
  }
];

let k = users.reduce((acc, curr) => acc += curr.age, 0);
console.log(k)