CODEWITHSUNDEEP
javascriptarrays
user20581800
user20581800

Reputation: 11

get sum total by using foreach

I am trying to get a total by using the forEach in javascript but failing somehow... It just lists the values rather than giving me the 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?
  });
}

Upvotes: 0

Views: 63

Answers (2)

Sundaramoorthy Anandh
Sundaramoorthy Anandh

Reputation: 601

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

const finances = [["Jan", 867884], ["Feb", 984655], ["Mar", 322013], ["Apr", -69417], ["May", 310503]];
 
    let total = 0;
    finances.forEach(item => total = item[1] + total);
    console.log(total)

Upvotes: 1

Daniel Benisti
Daniel Benisti

Reputation: 130

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

Upvotes: 0

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