mongodb Map-Reduce create javascript map code example

Example 1: js map filter reduce

const numbers = [1, 2, 3, 4];
const doubled = numbers.map(item => item * 2);
console.log(doubled); // [2, 4, 6, 8]

Example 2: js map filter reduce

const numbers = [1, 2, 3, 4];
const sum = numbers.reduce(function (result, item) {
  return result + item;
}, 0);
console.log(sum); // 10