get sum total by using foreach-CodePudding

I am trying to get a total by using the foreach in javascript but failing somehow...it just lists the values rather than give me total figure`

const finances = [
    ["Jan", 867884],
    ["Feb", 984655],
    ["Mar", 322013],
    ["Apr", -69417],
    ["May", 310503],
];

let sum2 = 0;
for (let i = 0; i < finances.length - 1; i  ) {
  let monthDiff = finances[i][1] - finances[i   1][1];
  // console.log(monthDiff)
//   console.log(typeof(monthDiff))
  const newArray = [monthDiff];
  // console.log(newArray)
  newArray.forEach((item) => {
    sum2  = item; 
    console.log(sum2); //listing values not giving me a total why?
  });
}

CodePudding user response：

if using a forEach is not mandatory i would switch to reduce. reduce give you the option to keep track of the previous value as first parameter of the callback. for more info follow the Link.

const array1 = [1, 2, 3, 4];
// 0   1   2   3   4
const initialValue = 0;
const sumWithInitial = array1.reduce(
  (accumulator, currentValue) => accumulator   currentValue,
  initialValue
);

console.log(sumWithInitial);
// expected output: 10

CodePudding user response：

You have to loop thru each array item and get the 1st index and add it with the current sum.. on first looping, zero is the current sum..

loop no. 1 - currentSum = 0, currentValue[1] = 867884

loop no. 2 - csum = 867884, cval[1] = 984655

loop no. 3 - csum = 867884 984655, cval[1] = 322013

...goes on until array end

const finances = [["Jan", 867884], ["Feb", 984655], ["Mar", 322013], ["Apr", -69417], ["May", 310503]];

const total = finances.reduce(
    (currentSum, currentValue) => currentValue[1]   currentSum
, 0); // initial sum is zero

console.log(total)

Interms of foreach

let total = 0;
finances.forEach(item => total = item[1]   total);
console.log(total)