how to simplify this function

Issue

I created a function that should return an array of numbers. it works, the only problem is that is really ugly and I was wonder if you know a better way to do it cause I can't.

totalMonth() {
    let arrSubKpiJan = [];
    let arrSubKpiFeb = [];
    let arrSubKpiMar = [];
    let arrSubKpiApr = [];
    let arrSubKpiMay = [];
    let arrSubKpiJun = [];
    let arrSubKpiJul = [];
    let arrSubKpiAug = [];
    let arrSubKpiSep = [];
    let arrSubKpiOct = [];
    let arrSubKpiNov = [];
    let arrSubKpiDec = [];

    for(let subkpi of this.overview) {
      arrSubKpiJan.push(subkpi.jan)
      arrSubKpiFeb.push(subkpi.feb)
      arrSubKpiMar.push(subkpi.mar)
      arrSubKpiApr.push(subkpi.apr)
      arrSubKpiMay.push(subkpi.may)
      arrSubKpiJun.push(subkpi.jun)
      arrSubKpiJul.push(subkpi.jul)
      arrSubKpiAug.push(subkpi.aug)
      arrSubKpiSep.push(subkpi.sep)
      arrSubKpiOct.push(subkpi.oct)
      arrSubKpiNov.push(subkpi.nov)
      arrSubKpiDec.push(subkpi.dec)

    }
    let sumJan = arrSubKpiJan.reduce((a, b) => a + b, 0);
    let sumFeb = arrSubKpiFeb.reduce((a, b) => a + b, 0);
    let sumMar = arrSubKpiMar.reduce((a, b) => a + b, 0);
    let sumApr = arrSubKpiApr.reduce((a, b) => a + b, 0);
    let sumMay = arrSubKpiMay.reduce((a, b) => a + b, 0);
    let sumJun = arrSubKpiJun.reduce((a, b) => a + b, 0);
    let sumJul = arrSubKpiJul.reduce((a, b) => a + b, 0);
    let sumAug = arrSubKpiAug.reduce((a, b) => a + b, 0);
    let sumSep = arrSubKpiSep.reduce((a, b) => a + b, 0);
    let sumOct = arrSubKpiOct.reduce((a, b) => a + b, 0);
    let sumNov = arrSubKpiNov.reduce((a, b) => a + b, 0);
    let sumDec = arrSubKpiDec.reduce((a, b) => a + b, 0);
    let arrMonths = [sumJan,
      sumFeb,
      sumMar,
      sumApr,
      sumMay,
      sumJun,
      sumJul,
      sumAug,
      sumSep,
      sumOct,
      sumNov,
      sumDec]
      return arrMonths
  }

so I m creating an array for each month of the year, then I pushing the values inside the single array always for each month, then with reduce() I'm doing the sum and in the end I'm returning the array. I know is really ugly to see it, but I don't know what to do to have the same behaviour. Thanks in advance

Solution

You can try this approach with Object.entries and using an object instead of an array to keep your result values.

function totalMonth() {
  const result = {}
  const predefinedKeys = ['jan', 'feb', 'mar', 'apr', 'may', 'jun', 'july', 'aug', 'sep', 'oct', 'nov', 'dec'];

  for (let subkpi of this.overview) {
    for (let [key, value] of Object.entries(subkpi)) {
      //if the key is not in predefined keys, we skip it
      if (!predefinedKeys.includes(key)) {
        continue;
      }

      //the object will be like result.jan, result.feb, and so on
      if (!result[key]) {
        result[key] = 0;
      }
      result[key] += value; //sum directly here
    }
  }
  return predefinedKeys.map(key => result[key]);
}

Answered By - Nick Vu