Answers for "javascript sum of values in object in object"

js get sum of array of objects

const getSumByKey = (arr, key) => {
  return arr.reduce((accumulator, current) => accumulator + Number(current[key]), 0)
}

arr = [{x:1}, {x:3}]
getSumByKey(arr, 'x') // returns 4

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
  });

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}