javascript sum array of objects code example

Example 1: javascript sum array of objects

arr = [{x:1}, {x:3}]

arr.reduce((accumulator, current) => accumulator + current.x, 0);

Example 2: 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 3: sum of array of objects javascript

var accounts = [
  { name: 'James Brown', msgCount: 123 },
  { name: 'Stevie Wonder', msgCount: 22 },
  { name: 'Sly Stone', msgCount: 16 },
  { name: 'Otis Redding', msgCount: 300 }  // Otis has the most messages
];

// get sum of msgCount prop across all objects in array
var msgTotal = accounts.reduce(function(prev, cur) {
  return prev + cur.msgCount;
}, 0);

console.log('Total Messages:', msgTotal); // Total Messages: 461

Example 4: 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}