how to calculate sum of array objects in javascript code example

Example 1: javascript sum array of objects

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

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

Example 2: 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

Example 3: 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}