Get the sum of all specified elements in an array of objects

Question

I have an array of objects as folllows

[
    {\"width\":128.90663423245883,\"height\":160,\"X\":0,\"Y\":140},
    {\"width\":277.0938568683375,\"height\":263,\"X         


        

Answer 1

Here is an example using a slice to first return the array with the correct length and the a reduce to return the sum

const getSum = (objNum, arr) => {
  const newArr =  arr.slice(0, objNum - 1)
  return newArr.reduce((current, next) => {
    return current + next.width;
  }, 0)
}

and in ES5

var getSum = (objNum, arr) => {
  vat newArr =  arr.slice(0, objNum - 1)
  return newArr.reduce(function(current, next) {
    return current + next.width;
  }, 0)
}

and in 1 line

const getSum = (objNum, arr) => arr.slice(0, objNum - 1).reduce((current, next) =>  current + next.width, 0)