How to use for to sum a range in google app script?

Question

I want create a simple custom sum formula in google Spreadsheets using google app Script.

 function somaDias(range, days) {
   var sum = 0;

   for(i=0; i<days; i++){
     sum = sum + range[i];
  }


    return soma;
    }

I will use this function in a report that has a column with monetary values for each day of the month. The idea is to select the whole column of values, pass it as a range and them sum this values up to a day of the month. I know there is something wrong with

  sum = sum + range[i];

because, when I test it with a column that has only 1... the return is "0111111"

=somaDias(C9:C15;6) // should return 6, but it returns 0111111

I don´t want to use =sum(), because the range changes according to the day. I want to pass as the range the 30 days of the month and then pass the number of days I want to sum. If I used sum, I would have to reselect the range everyday....

What I´m doing wrong?

Answer 1

Why not using the spreadsheet built in function SUM() ? (doc here)

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edit following comment.

I don't like custom functions but here is a way to achieve what you want : use only 1 parameter = number of days, it will count from the first column.

function somaDias(days) {
  var sum = 0;
  var sh = SpreadsheetApp.getActiveSheet();
  var values = sh.getRange(sh.getActiveCell().getRowIndex(),1,1,days).getValues();

  for(var i in values[0]){
    sum += values[0][i];
  }
  return sum;
}