how to sum values in an object in javascript code example

Example 1: javascript sum of number in object array

run.addEventListener("click", function () {
    let sum = people.reduce(function (a, b) { // function(previousValue, currentValue)
      return {
        age: a.age + b.age, //select age in object array
      };
    });
    console.log(sum); //output sum of ages
  });

Example 2: javascript object array sum of values in object

const fruitTally = fruit.reduce((currentTally, currentFruit) => {
  currentTally[currentFruit] = (currentTally[currentFruit] || 0) + 1 
  return currentTally
} , {})
// returns {"apple":3,"banana":3,"cherry":2,"mango":2,"apricot":1,"guava":2}